Lint: Update linter config, fix all linter issues

Signed-off-by: Knut Ahlers <knut@ahlers.me>

.golangci.yml

@@ -11,6 +11,61 @@ run:
 output:
   format: tab
 
+issues:
+  # This disables the included exclude-list in golangci-lint as that
+  # list for example fully hides G304 gosec rule, errcheck, exported
+  # rule of revive and other errors one really wants to see.
+  # Smme detail: https://github.com/golangci/golangci-lint/issues/456
+  exclude-use-default: false
+  # Don't limit the number of shown issues: Report ALL of them
+  max-issues-per-linter: 0
+  max-same-issues: 0
+
+linters:
+  disable-all: true
+  enable:
+    - asciicheck    # Simple linter to check that your code does not contain non-ASCII identifiers [fast: true, auto-fix: false]
+    - bidichk       # Checks for dangerous unicode character sequences [fast: true, auto-fix: false]
+    - bodyclose     # checks whether HTTP response body is closed successfully [fast: true, auto-fix: false]
+    - containedctx  # containedctx is a linter that detects struct contained context.Context field [fast: true, auto-fix: false]
+    - contextcheck  # check the function whether use a non-inherited context [fast: false, auto-fix: false]
+    - depguard      # Go linter that checks if package imports are in a list of acceptable packages [fast: true, auto-fix: false]
+    - dogsled       # Checks assignments with too many blank identifiers (e.g. x, _, _, _, := f()) [fast: true, auto-fix: false]
+    - durationcheck # check for two durations multiplied together [fast: false, auto-fix: false]
+    - errcheck      # Errcheck is a program for checking for unchecked errors in go programs. These unchecked errors can be critical bugs in some cases [fast: false, auto-fix: false]
+    - errchkjson    # Checks types passed to the json encoding functions. Reports unsupported types and optionally reports occations, where the check for the returned error can be omitted. [fast: false, auto-fix: false]
+    - exportloopref # checks for pointers to enclosing loop variables [fast: true, auto-fix: false]
+    - forbidigo     # Forbids identifiers [fast: true, auto-fix: false]
+    - funlen        # Tool for detection of long functions [fast: true, auto-fix: false]
+    - gocognit      # Computes and checks the cognitive complexity of functions [fast: true, auto-fix: false]
+    - goconst       # Finds repeated strings that could be replaced by a constant [fast: true, auto-fix: false]
+    - gocritic      # The most opinionated Go source code linter [fast: true, auto-fix: false]
+    - gocyclo       # Computes and checks the cyclomatic complexity of functions [fast: true, auto-fix: false]
+    - godox         # Tool for detection of FIXME, TODO and other comment keywords [fast: true, auto-fix: false]
+    - gofmt         # Gofmt checks whether code was gofmt-ed. By default this tool runs with -s option to check for code simplification [fast: true, auto-fix: true]
+    - gofumpt       # Gofumpt checks whether code was gofumpt-ed. [fast: true, auto-fix: true]
+    - goimports     # Goimports does everything that gofmt does. Additionally it checks unused imports [fast: true, auto-fix: true]
+    - gomnd         # An analyzer to detect magic numbers. [fast: true, auto-fix: false]
+    - gosec         # Inspects source code for security problems [fast: true, auto-fix: false]
+    - gosimple      # Linter for Go source code that specializes in simplifying a code [fast: true, auto-fix: false]
+    - govet         # Vet examines Go source code and reports suspicious constructs, such as Printf calls whose arguments do not align with the format string [fast: true, auto-fix: false]
+    - ineffassign   # Detects when assignments to existing variables are not used [fast: true, auto-fix: false]
+    - misspell      # Finds commonly misspelled English words in comments [fast: true, auto-fix: true]
+    - nakedret      # Finds naked returns in functions greater than a specified function length [fast: true, auto-fix: false]
+    - nilerr        # Finds the code that returns nil even if it checks that the error is not nil. [fast: false, auto-fix: false]
+    - nilnil        # Checks that there is no simultaneous return of `nil` error and an invalid value. [fast: false, auto-fix: false]
+    - noctx         # noctx finds sending http request without context.Context [fast: true, auto-fix: false]
+    - nolintlint    # Reports ill-formed or insufficient nolint directives [fast: true, auto-fix: false]
+    - revive        # Fast, configurable, extensible, flexible, and beautiful linter for Go. Drop-in replacement of golint. [fast: false, auto-fix: false]
+    - staticcheck   # Staticcheck is a go vet on steroids, applying a ton of static analysis checks [fast: true, auto-fix: false]
+    - stylecheck    # Stylecheck is a replacement for golint [fast: true, auto-fix: false]
+    - tenv          # tenv is analyzer that detects using os.Setenv instead of t.Setenv since Go1.17 [fast: false, auto-fix: false]
+    - typecheck     # Like the front-end of a Go compiler, parses and type-checks Go code [fast: true, auto-fix: false]
+    - unconvert     # Remove unnecessary type conversions [fast: true, auto-fix: false]
+    - unused        # Checks Go code for unused constants, variables, functions and types [fast: false, auto-fix: false]
+    - wastedassign  # wastedassign finds wasted assignment statements. [fast: false, auto-fix: false]
+    - wrapcheck     # Checks that errors returned from external packages are wrapped [fast: false, auto-fix: false]
+
 linters-settings:
   forbidigo:
     forbid:
@@ -29,41 +84,96 @@ linters-settings:
       mnd:
         ignored-functions: 'strconv.(?:Format|Parse)\B+'
 
-linters:
-  disable-all: true
-  enable:
-    - asciicheck    # Simple linter to check that your code does not contain non-ASCII identifiers [fast: true, auto-fix: false]
-    - bodyclose     # checks whether HTTP response body is closed successfully [fast: true, auto-fix: false]
-    - deadcode      # Finds unused code [fast: true, auto-fix: false]
-    - depguard      # Go linter that checks if package imports are in a list of acceptable packages [fast: true, auto-fix: false]
-    - dogsled       # Checks assignments with too many blank identifiers (e.g. x, _, _, _, := f()) [fast: true, auto-fix: false]
-    - exportloopref # checks for pointers to enclosing loop variables [fast: true, auto-fix: false]
-    - forbidigo     # Forbids identifiers [fast: true, auto-fix: false]
-    - funlen        # Tool for detection of long functions [fast: true, auto-fix: false]
-    - gocognit      # Computes and checks the cognitive complexity of functions [fast: true, auto-fix: false]
-    - goconst       # Finds repeated strings that could be replaced by a constant [fast: true, auto-fix: false]
-    - gocritic      # The most opinionated Go source code linter [fast: true, auto-fix: false]
-    - gocyclo       # Computes and checks the cyclomatic complexity of functions [fast: true, auto-fix: false]
-    - godox         # Tool for detection of FIXME, TODO and other comment keywords [fast: true, auto-fix: false]
-    - gofmt         # Gofmt checks whether code was gofmt-ed. By default this tool runs with -s option to check for code simplification [fast: true, auto-fix: true]
-    - gofumpt       # Gofumpt checks whether code was gofumpt-ed. [fast: true, auto-fix: true]
-    - goimports     # Goimports does everything that gofmt does. Additionally it checks unused imports [fast: true, auto-fix: true]
-    - gomnd         # An analyzer to detect magic numbers. [fast: true, auto-fix: false]
-    - gosec         # Inspects source code for security problems [fast: true, auto-fix: false]
-    - gosimple      # Linter for Go source code that specializes in simplifying a code [fast: true, auto-fix: false]
-    - govet         # Vet examines Go source code and reports suspicious constructs, such as Printf calls whose arguments do not align with the format string [fast: true, auto-fix: false]
-    - ineffassign   # Detects when assignments to existing variables are not used [fast: true, auto-fix: false]
-    - misspell      # Finds commonly misspelled English words in comments [fast: true, auto-fix: true]
-    - nakedret      # Finds naked returns in functions greater than a specified function length [fast: true, auto-fix: false]
-    - noctx         # noctx finds sending http request without context.Context [fast: true, auto-fix: false]
-    - nolintlint    # Reports ill-formed or insufficient nolint directives [fast: true, auto-fix: false]
-    - revive        # Fast, configurable, extensible, flexible, and beautiful linter for Go. Drop-in replacement of golint. [fast: false, auto-fix: false]
-    - staticcheck   # Staticcheck is a go vet on steroids, applying a ton of static analysis checks [fast: true, auto-fix: false]
-    - structcheck   # Finds unused struct fields [fast: true, auto-fix: false]
-    - stylecheck    # Stylecheck is a replacement for golint [fast: true, auto-fix: false]
-    - typecheck     # Like the front-end of a Go compiler, parses and type-checks Go code [fast: true, auto-fix: false]
-    - unconvert     # Remove unnecessary type conversions [fast: true, auto-fix: false]
-    - unused        # Checks Go code for unused constants, variables, functions and types [fast: false, auto-fix: false]
-    - varcheck      # Finds unused global variables and constants [fast: true, auto-fix: false]
+  revive:
+    rules:
+      #- name: add-constant           # Suggests using constant for magic numbers and string literals
+                                      # Opinion: Makes sense for strings, not for numbers but checks numbers
+      #- name: argument-limit         # Specifies the maximum number of arguments a function can receive | Opinion: Don't need this
+      - name: atomic                  # Check for common mistaken usages of the `sync/atomic` package
+      - name: banned-characters       # Checks banned characters in identifiers
+        arguments:
+          - ';' # Greek question mark
+      - name: bare-return             # Warns on bare returns
+      - name: blank-imports           # Disallows blank imports
+      - name: bool-literal-in-expr    # Suggests removing Boolean literals from logic expressions
+      - name: call-to-gc              # Warns on explicit call to the garbage collector
+      #- name: cognitive-complexity   # Sets restriction for maximum Cognitive complexity.
+                                      # There is a dedicated linter for this
+      - name: confusing-naming        # Warns on methods with names that differ only by capitalization
+      - name: confusing-results       # Suggests to name potentially confusing function results
+      - name: constant-logical-expr   # Warns on constant logical expressions
+      - name: context-as-argument     # `context.Context` should be the first argument of a function.
+      - name: context-keys-type       # Disallows the usage of basic types in `context.WithValue`.
+      #- name: cyclomatic             # Sets restriction for maximum Cyclomatic complexity.
+                                      # There is a dedicated linter for this
+      #- name: datarace               # Spots potential dataraces
+                                      # Is not (yet) available?
+      - name: deep-exit               # Looks for program exits in funcs other than `main()` or `init()`
+      - name: defer                   # Warns on some [defer gotchas](https://blog.learngoprogramming.com/5-gotchas-of-defer-in-go-golang-part-iii-36a1ab3d6ef1)
+      - name: dot-imports             # Forbids `.` imports.
+      - name: duplicated-imports      # Looks for packages that are imported two or more times
+      - name: early-return            # Spots if-then-else statements that can be refactored to simplify code reading
+      - name: empty-block             # Warns on empty code blocks
+      - name: empty-lines             # Warns when there are heading or trailing newlines in a block
+      - name: errorf                  # Should replace `errors.New(fmt.Sprintf())` with `fmt.Errorf()`
+      - name: error-naming            # Naming of error variables.
+      - name: error-return            # The error return parameter should be last.
+      - name: error-strings           # Conventions around error strings.
+      - name: exported                # Naming and commenting conventions on exported symbols.
+        arguments: ['sayRepetitiveInsteadOfStutters']
+      #- name: file-header            # Header which each file should have.
+                                      # Useless without config, have no config for it
+      - name: flag-parameter          # Warns on boolean parameters that create a control coupling
+      #- name: function-length        # Warns on functions exceeding the statements or lines max
+                                      # There is a dedicated linter for this
+      #- name: function-result-limit  # Specifies the maximum number of results a function can return
+                                      # Opinion: Don't need this
+      - name: get-return              # Warns on getters that do not yield any result
+      - name: identical-branches      # Spots if-then-else statements with identical `then` and `else` branches
+      - name: if-return               # Redundant if when returning an error.
+      #- name: imports-blacklist      # Disallows importing the specified packages
+                                      # Useless without config, have no config for it
+      - name: import-shadowing        # Spots identifiers that shadow an import
+      - name: increment-decrement     # Use `i++` and `i--` instead of `i += 1` and `i -= 1`.
+      - name: indent-error-flow       # Prevents redundant else statements.
+      #- name: line-length-limit      # Specifies the maximum number of characters in a lined
+                                      # There is a dedicated linter for this
+      #- name: max-public-structs     # The maximum number of public structs in a file.
+                                      # Opinion: Don't need this
+      - name: modifies-parameter      # Warns on assignments to function parameters
+      - name: modifies-value-receiver # Warns on assignments to value-passed method receivers
+      #- name: nested-structs         # Warns on structs within structs
+                                      # Opinion: Don't need this
+      - name: optimize-operands-order # Checks inefficient conditional expressions
+      #- name: package-comments       # Package commenting conventions.
+                                      # Opinion: Don't need this
+      - name: range                   # Prevents redundant variables when iterating over a collection.
+      - name: range-val-address       # Warns if address of range value is used dangerously
+      - name: range-val-in-closure    # Warns if range value is used in a closure dispatched as goroutine
+      - name: receiver-naming         # Conventions around the naming of receivers.
+      - name: redefines-builtin-id    # Warns on redefinitions of builtin identifiers
+      #- name: string-format          # Warns on specific string literals that fail one or more user-configured regular expressions
+                                      # Useless without config, have no config for it
+      - name: string-of-int           # Warns on suspicious casts from int to string
+      - name: struct-tag              # Checks common struct tags like `json`,`xml`,`yaml`
+      - name: superfluous-else        # Prevents redundant else statements (extends indent-error-flow)
+      - name: time-equal              # Suggests to use `time.Time.Equal` instead of `==` and `!=` for equality check time.
+      - name: time-naming             # Conventions around the naming of time variables.
+      - name: unconditional-recursion # Warns on function calls that will lead to (direct) infinite recursion
+      - name: unexported-naming       # Warns on wrongly named un-exported symbols
+      - name: unexported-return       # Warns when a public return is from unexported type.
+      - name: unhandled-error         # Warns on unhandled errors returned by funcion calls
+        arguments:
+          - "fmt.(Fp|P)rint(f|ln|)"
+      - name: unnecessary-stmt        # Suggests removing or simplifying unnecessary statements
+      - name: unreachable-code        # Warns on unreachable code
+      - name: unused-parameter        # Suggests to rename or remove unused function parameters
+      - name: unused-receiver         # Suggests to rename or remove unused method receivers
+      #- name: use-any                # Proposes to replace `interface{}` with its alias `any`
+                                      # Is not (yet) available?
+      - name: useless-break           # Warns on useless `break` statements in case clauses
+      - name: var-declaration         # Reduces redundancies around variable declaration.
+      - name: var-naming              # Naming rules.
+      - name: waitgroup-by-value      # Warns on functions taking sync.WaitGroup as a by-value parameter
 
 ...

api.go

@@ -22,7 +22,7 @@ import (
 )
 
 type (
-	APICatalogEntry struct {
+	apiCatalogEntry struct {
 		database.CatalogEntry
 		database.CatalogMeta
 	}
@@ -35,10 +35,10 @@ func buildFullURL(u *url.URL, _ error) string {
 	}, "/")
 }
 
-func catalogEntryToAPICatalogEntry(ce database.CatalogEntry) (APICatalogEntry, error) {
+func catalogEntryToAPICatalogEntry(ce database.CatalogEntry) (apiCatalogEntry, error) {
 	cm, err := storage.Catalog.GetMeta(&ce)
 	if err != nil {
-		return APICatalogEntry{}, errors.Wrap(err, "fetching catalog meta")
+		return apiCatalogEntry{}, errors.Wrap(err, "fetching catalog meta")
 	}
 
 	for _, l := range fetcher.Get(ce.Fetcher).Links(ce.FetcherConfig) {
@@ -55,7 +55,7 @@ func catalogEntryToAPICatalogEntry(ce database.CatalogEntry) (APICatalogEntry, e
 		}
 	}
 
-	return APICatalogEntry{CatalogEntry: ce, CatalogMeta: *cm}, nil
+	return apiCatalogEntry{CatalogEntry: ce, CatalogMeta: *cm}, nil
 }
 
 func handleBadgeRedirect(w http.ResponseWriter, r *http.Request) {
@@ -142,8 +142,8 @@ func handleCatalogGetVersion(w http.ResponseWriter, r *http.Request) {
 	fmt.Fprint(w, cm.CurrentVersion)
 }
 
-func handleCatalogList(w http.ResponseWriter, r *http.Request) {
-	out := make([]APICatalogEntry, len(configFile.Catalog))
+func handleCatalogList(w http.ResponseWriter, _ *http.Request) {
+	out := make([]apiCatalogEntry, len(configFile.Catalog))
 
 	for i := range configFile.Catalog {
 		ce := configFile.Catalog[i]

frontend.go

@@ -7,6 +7,8 @@ import (
 	"path/filepath"
 
 	"github.com/pkg/errors"
+
+	"github.com/Luzifer/go-latestver/internal/helpers"
 )
 
 func handleSinglePage(w http.ResponseWriter, r *http.Request) {
@@ -19,16 +21,15 @@ func handleSinglePage(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	for _, path := range []string{
+	for _, frontendPath := range []string{
 		filepath.Join("frontend", path.Base(urlPath)),
 		filepath.Join("frontend", "index.html"),
 	} {
-		f, err := frontendFS.Open(path)
+		f, err := frontendFS.Open(frontendPath)
 		switch {
-
 		case err == nil:
 			// file is opened, serve it
-			defer f.Close()
+			defer func() { helpers.LogIfErr(f.Close(), "closing frontend file after serve") }() //revive:disable-line:defer Fine here as it will only open one file
 
 			stat, err := f.Stat()
 			if err != nil {

internal/config/config.go

@@ -1,3 +1,5 @@
+// Package config holds the definition of the configuration file and
+// some methods to load and validate it
 package config
 
 import (
@@ -9,23 +11,30 @@ import (
 
 	"github.com/Luzifer/go-latestver/internal/database"
 	"github.com/Luzifer/go-latestver/internal/fetcher"
+	"github.com/Luzifer/go-latestver/internal/helpers"
 )
 
+// ErrCatalogEntryNotFound signalizes a catalog entry with the given
+// name was not found
 var ErrCatalogEntryNotFound = errors.New("catalog entry not found")
 
 type (
+	// File represents the configuration file content
 	File struct {
 		Catalog       []database.CatalogEntry `yaml:"catalog"`
 		CheckInterval time.Duration           `yaml:"check_interval"`
 	}
 )
 
+// New creates a new empty File object with defaults
 func New() *File {
 	return &File{
 		CheckInterval: time.Hour,
 	}
 }
 
+// CatalogEntryByTag retrieves a catalog entry by its name or returns
+// and ErrCatalogEntryNotFound if it does not exist
 func (f File) CatalogEntryByTag(name, tag string) (database.CatalogEntry, error) {
 	for i := range f.Catalog {
 		ce := f.Catalog[i]
@@ -37,12 +46,14 @@ func (f File) CatalogEntryByTag(name, tag string) (database.CatalogEntry, error)
 	return database.CatalogEntry{}, ErrCatalogEntryNotFound
 }
 
+// Load loads the contents of the configuration file in the filesystem
+// into the File object
 func (f *File) Load(filepath string) error {
-	fh, err := os.Open(filepath)
+	fh, err := os.Open(filepath) //#nosec:G304 // As this is the config file and needs a location this is fine
 	if err != nil {
 		return errors.Wrap(err, "opening config file")
 	}
-	defer fh.Close()
+	defer func() { helpers.LogIfErr(fh.Close(), "closing config after load") }()
 
 	dec := yaml.NewDecoder(fh)
 	dec.KnownFields(true)
@@ -50,14 +61,16 @@ func (f *File) Load(filepath string) error {
 	return errors.Wrap(dec.Decode(f), "decoding config")
 }
 
+// ValidateCatalog checks whether invalid fetchers are used or the
+// configuration of the fetcher is not suitable for the given fetcher
 func (f File) ValidateCatalog() error {
 	for i, ce := range f.Catalog {
-		f := fetcher.Get(ce.Fetcher)
-		if f == nil {
+		fi := fetcher.Get(ce.Fetcher)
+		if fi == nil {
 			return errors.Errorf("catalog entry %d has unknown fetcher", i)
 		}
 
-		if err := f.Validate(ce.FetcherConfig); err != nil {
+		if err := fi.Validate(ce.FetcherConfig); err != nil {
 			return errors.Wrapf(err, "catalog entry %d has invalid fetcher config", i)
 		}
 	}

internal/database/db.go

@@ -1,3 +1,5 @@
+// Package database implements a wrapper around the real database
+// with some helper functions to store catalog / log entries
 package database
 
 import (
@@ -14,6 +16,7 @@ import (
 )
 
 type (
+	// Client represents a database client
 	Client struct {
 		Catalog CatalogMetaStore
 		Logs    LogStore
@@ -30,6 +33,9 @@ type (
 	}
 )
 
+// NewClient creates a new Client and connects to the database using
+// some default configurations. The database is automatically
+// initialized with required tables.
 func NewClient(dbtype, dsn string) (*Client, error) {
 	c := &Client{}
 	c.Catalog = CatalogMetaStore{c}
@@ -75,6 +81,7 @@ func NewClient(dbtype, dsn string) (*Client, error) {
 	return c, nil
 }
 
+// Migrate executes database migrations for all required types
 func (c Client) Migrate(dest *Client) error {
 	for _, m := range []migrator{
 		c.Catalog,

internal/database/store.go

@@ -13,6 +13,7 @@ import (
 )
 
 type (
+	// CatalogEntry represents the entry in the config file
 	CatalogEntry struct {
 		Name string `json:"name" yaml:"name"`
 		Tag  string `json:"tag" yaml:"tag"`
@@ -25,12 +26,14 @@ type (
 		Links []CatalogLink `json:"links" yaml:"links"`
 	}
 
+	// CatalogLink represents a link assigned to a CatalogEntry
 	CatalogLink struct {
 		IconClass string `json:"icon_class" yaml:"icon_class"`
 		Name      string `json:"name" yaml:"name"`
 		URL       string `json:"url" yaml:"url"`
 	}
 
+	// CatalogMeta contains meta-information about the catalog entry
 	CatalogMeta struct {
 		CatalogName    string     `gorm:"primaryKey" json:"-"`
 		CatalogTag     string     `gorm:"primaryKey" json:"-"`
@@ -40,6 +43,7 @@ type (
 		VersionTime    *time.Time `json:"version_time,omitempty"`
 	}
 
+	// LogEntry represents a single version change for a given catalog entry
 	LogEntry struct {
 		CatalogName string    `gorm:"index:catalog_key" json:"catalog_name"`
 		CatalogTag  string    `gorm:"index:catalog_key" json:"catalog_tag"`
@@ -48,17 +52,21 @@ type (
 		VersionFrom string    `json:"version_from"`
 	}
 
+	// CatalogMetaStore is an accessor for the meta store and wraps a Client
 	CatalogMetaStore struct {
 		c *Client
 	}
 
+	// LogStore is an accessor for the log store and wraps a Client
 	LogStore struct {
 		c *Client
 	}
 )
 
+// Key returns the name / tag combination as a single key
 func (c CatalogEntry) Key() string { return strings.Join([]string{c.Name, c.Tag}, ":") }
 
+// GetMeta fetches the current database stored CatalogMeta for the CatalogEntry
 func (c CatalogMetaStore) GetMeta(ce *CatalogEntry) (*CatalogMeta, error) {
 	out := &CatalogMeta{
 		CatalogName: ce.Name,
@@ -77,6 +85,7 @@ func (c CatalogMetaStore) GetMeta(ce *CatalogEntry) (*CatalogMeta, error) {
 	return out, errors.Wrap(err, "querying metadata")
 }
 
+// Migrate applies the updated database schema for the CatalogMetaStore
 func (c CatalogMetaStore) Migrate(dest *Client) error {
 	var metas []*CatalogMeta
 	if err := c.c.db.Find(&metas).Error; err != nil {
@@ -92,6 +101,7 @@ func (c CatalogMetaStore) Migrate(dest *Client) error {
 	return nil
 }
 
+// PutMeta stores the updated CatalogMeta
 func (c CatalogMetaStore) PutMeta(cm *CatalogMeta) error {
 	return errors.Wrap(
 		c.c.db.Clauses(clause.OnConflict{UpdateAll: true}).Create(cm).Error,
@@ -103,6 +113,7 @@ func (c CatalogMetaStore) ensureTable() error {
 	return errors.Wrap(c.c.db.AutoMigrate(&CatalogMeta{}), "applying migration")
 }
 
+// Add creates a new LogEntry inside the LogStore
 func (l LogStore) Add(le *LogEntry) error {
 	return errors.Wrap(
 		l.c.db.Create(le).Error,
@@ -110,14 +121,17 @@ func (l LogStore) Add(le *LogEntry) error {
 	)
 }
 
+// List retrieves unfiltered log entries by page
 func (l LogStore) List(num, page int) ([]LogEntry, error) {
 	return l.listWithFilter(l.c.db, num, page)
 }
 
+// ListForCatalogEntry retrieves filered log entries by page
 func (l LogStore) ListForCatalogEntry(ce *CatalogEntry, num, page int) ([]LogEntry, error) {
 	return l.listWithFilter(l.c.db.Where(&LogEntry{CatalogName: ce.Name, CatalogTag: ce.Tag}), num, page)
 }
 
+// Migrate applies the updated database schema for the LogStore
 func (l LogStore) Migrate(dest *Client) error {
 	var logs []*LogEntry
 	if err := l.c.db.Find(&logs).Error; err != nil {
@@ -133,7 +147,7 @@ func (l LogStore) Migrate(dest *Client) error {
 	return nil
 }
 
-func (l LogStore) listWithFilter(filter *gorm.DB, num, page int) ([]LogEntry, error) {
+func (LogStore) listWithFilter(filter *gorm.DB, num, page int) ([]LogEntry, error) {
 	var out []LogEntry
 	return out, errors.Wrap(
 		filter.

internal/fetcher/atlassian.go

@@ -4,7 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"sort"
 	"strings"
@@ -13,6 +13,7 @@ import (
 	"github.com/pkg/errors"
 
 	"github.com/Luzifer/go-latestver/internal/database"
+	"github.com/Luzifer/go-latestver/internal/helpers"
 	"github.com/Luzifer/go_helpers/v2/fieldcollection"
 )
 
@@ -27,12 +28,14 @@ var (
 )
 
 type (
+	// AtlassianFetcher implements the fetcher interface to monitor Atlassian products
 	AtlassianFetcher struct{}
 )
 
 func init() { registerFetcher("atlassian", func() Fetcher { return &AtlassianFetcher{} }) }
 
-func (a AtlassianFetcher) FetchVersion(ctx context.Context, attrs *fieldcollection.FieldCollection) (string, time.Time, error) {
+// FetchVersion retrieves the latest version for the catalog entry
+func (AtlassianFetcher) FetchVersion(ctx context.Context, attrs *fieldcollection.FieldCollection) (string, time.Time, error) {
 	url := fmt.Sprintf("https://my.atlassian.com/download/feeds/current/%s.json", attrs.MustString("product", nil))
 
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
@@ -44,9 +47,9 @@ func (a AtlassianFetcher) FetchVersion(ctx context.Context, attrs *fieldcollecti
 	if err != nil {
 		return "", time.Time{}, errors.Wrap(err, "executing request")
 	}
-	defer resp.Body.Close()
+	defer func() { helpers.LogIfErr(resp.Body.Close(), "closing response body after read") }()
 
-	body, err := ioutil.ReadAll(resp.Body)
+	body, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return "", time.Time{}, errors.Wrap(err, "reading response body")
 	}
@@ -103,10 +106,12 @@ func (a AtlassianFetcher) FetchVersion(ctx context.Context, attrs *fieldcollecti
 	return "", time.Time{}, ErrNoVersionFound
 }
 
-func (AtlassianFetcher) Links(attrs *fieldcollection.FieldCollection) []database.CatalogLink {
+// Links retrieves a collection of links for the fetcher
+func (AtlassianFetcher) Links(_ *fieldcollection.FieldCollection) []database.CatalogLink {
 	return nil
 }
 
+// Validate validates the configuration given to the fetcher
 func (AtlassianFetcher) Validate(attrs *fieldcollection.FieldCollection) error {
 	// @attr product required string "" Lowercase name of the product to fetch (e.g. confluence, crowd, jira-software, ...)
 	if v, err := attrs.String("product"); err != nil || v == "" {

internal/fetcher/git.go

@@ -20,12 +20,14 @@ import (
  */
 
 type (
+	// GitTagFetcher implements the fetcher interface to monitor tags in a git repository
 	GitTagFetcher struct{}
 )
 
 func init() { registerFetcher("git_tag", func() Fetcher { return &GitTagFetcher{} }) }
 
-func (g GitTagFetcher) FetchVersion(ctx context.Context, attrs *fieldcollection.FieldCollection) (string, time.Time, error) {
+// FetchVersion retrieves the latest version for the catalog entry
+func (g GitTagFetcher) FetchVersion(_ context.Context, attrs *fieldcollection.FieldCollection) (string, time.Time, error) {
 	repo, err := git.Init(memory.NewStorage(), nil)
 	if err != nil {
 		return "", time.Time{}, errors.Wrap(err, "opening in-mem repo")
@@ -79,11 +81,13 @@ func (g GitTagFetcher) FetchVersion(ctx context.Context, attrs *fieldcollection.
 	return latestTag.Name().Short(), latestTagTime, nil
 }
 
-func (g GitTagFetcher) Links(attrs *fieldcollection.FieldCollection) []database.CatalogLink {
+// Links retrieves a collection of links for the fetcher
+func (GitTagFetcher) Links(_ *fieldcollection.FieldCollection) []database.CatalogLink {
 	return nil
 }
 
-func (g GitTagFetcher) Validate(attrs *fieldcollection.FieldCollection) error {
+// Validate validates the configuration given to the fetcher
+func (GitTagFetcher) Validate(attrs *fieldcollection.FieldCollection) error {
 	// @attr remote required string "" Repository remote to fetch the tags from (should accept everything you can use in `git remote set-url` command)
 	if v, err := attrs.String("remote"); err != nil || v == "" {
 		return errors.New("remote is expected to be non-empty string")
@@ -92,7 +96,7 @@ func (g GitTagFetcher) Validate(attrs *fieldcollection.FieldCollection) error {
 	return nil
 }
 
-func (g GitTagFetcher) tagRefToTime(repo *git.Repository, tag *plumbing.Reference) (time.Time, error) {
+func (GitTagFetcher) tagRefToTime(repo *git.Repository, tag *plumbing.Reference) (time.Time, error) {
 	tagObj, err := repo.TagObject(tag.Hash())
 	if err == nil {
 		// Annotated tag: Take the time of the tag

internal/fetcher/github.go

@@ -11,6 +11,7 @@ import (
 	"github.com/pkg/errors"
 
 	"github.com/Luzifer/go-latestver/internal/database"
+	"github.com/Luzifer/go-latestver/internal/helpers"
 	"github.com/Luzifer/go_helpers/v2/fieldcollection"
 )
 
@@ -22,6 +23,7 @@ import (
 const githubHTTPTimeout = 2 * time.Second
 
 type (
+	// GithubReleaseFetcher implements the fetcher interface to monitor releases in a Github repository
 	GithubReleaseFetcher struct{}
 
 	githubRelease struct {
@@ -33,7 +35,8 @@ type (
 
 func init() { registerFetcher("github_release", func() Fetcher { return &GithubReleaseFetcher{} }) }
 
-func (g GithubReleaseFetcher) FetchVersion(ctx context.Context, attrs *fieldcollection.FieldCollection) (string, time.Time, error) {
+// FetchVersion retrieves the latest version for the catalog entry
+func (GithubReleaseFetcher) FetchVersion(ctx context.Context, attrs *fieldcollection.FieldCollection) (string, time.Time, error) {
 	ctx, cancel := context.WithTimeout(ctx, githubHTTPTimeout)
 	defer cancel()
 
@@ -56,11 +59,11 @@ func (g GithubReleaseFetcher) FetchVersion(ctx context.Context, attrs *fieldcoll
 	if err != nil {
 		return "", time.Time{}, errors.Wrap(err, "executing request")
 	}
+	defer func() { helpers.LogIfErr(resp.Body.Close(), "closing response body after read") }()
 
 	if resp.StatusCode != http.StatusOK {
 		return "", time.Time{}, errors.Errorf("unexpected HTTP status %d", resp.StatusCode)
 	}
-	defer resp.Body.Close()
 
 	var payload []githubRelease
 	if err = json.NewDecoder(resp.Body).Decode(&payload); err != nil {
@@ -85,7 +88,8 @@ func (g GithubReleaseFetcher) FetchVersion(ctx context.Context, attrs *fieldcoll
 	return release.TagName, release.PublishedAt, nil
 }
 
-func (g GithubReleaseFetcher) Links(attrs *fieldcollection.FieldCollection) []database.CatalogLink {
+// Links retrieves a collection of links for the fetcher
+func (GithubReleaseFetcher) Links(attrs *fieldcollection.FieldCollection) []database.CatalogLink {
 	return []database.CatalogLink{
 		{
 			IconClass: "fab fa-github",
@@ -95,7 +99,8 @@ func (g GithubReleaseFetcher) Links(attrs *fieldcollection.FieldCollection) []da
 	}
 }
 
-func (g GithubReleaseFetcher) Validate(attrs *fieldcollection.FieldCollection) error {
+// Validate validates the configuration given to the fetcher
+func (GithubReleaseFetcher) Validate(attrs *fieldcollection.FieldCollection) error {
 	// @attr repository required string "" Repository to fetch in form `owner/repo`
 	if v, err := attrs.String("repository"); err != nil || v == "" {
 		return errors.New("repository is expected to be non-empty string")

internal/fetcher/html.go

@@ -22,12 +22,14 @@ import (
 var htmlFetcherDefaultRegex = `(v?(?:[0-9]+\.?){2,})`
 
 type (
+	// HTMLFetcher implements the fetcher interface to monitor versions on websites by xpath queries
 	HTMLFetcher struct{}
 )
 
 func init() { registerFetcher("html", func() Fetcher { return &HTMLFetcher{} }) }
 
-func (h HTMLFetcher) FetchVersion(ctx context.Context, attrs *fieldcollection.FieldCollection) (string, time.Time, error) {
+// FetchVersion retrieves the latest version for the catalog entry
+func (HTMLFetcher) FetchVersion(_ context.Context, attrs *fieldcollection.FieldCollection) (string, time.Time, error) {
 	doc, err := htmlquery.LoadURL(attrs.MustString("url", nil))
 	if err != nil {
 		return "", time.Time{}, errors.Wrap(err, "loading URL")
@@ -58,7 +60,8 @@ func (h HTMLFetcher) FetchVersion(ctx context.Context, attrs *fieldcollection.Fi
 	return match[1], time.Now(), nil
 }
 
-func (h HTMLFetcher) Links(attrs *fieldcollection.FieldCollection) []database.CatalogLink {
+// Links retrieves a collection of links for the fetcher
+func (HTMLFetcher) Links(attrs *fieldcollection.FieldCollection) []database.CatalogLink {
 	return []database.CatalogLink{
 		{
 			IconClass: "fas fa-globe",
@@ -68,7 +71,8 @@ func (h HTMLFetcher) Links(attrs *fieldcollection.FieldCollection) []database.Ca
 	}
 }
 
-func (h HTMLFetcher) Validate(attrs *fieldcollection.FieldCollection) error {
+// Validate validates the configuration given to the fetcher
+func (HTMLFetcher) Validate(attrs *fieldcollection.FieldCollection) error {
 	// @attr url required string "" URL to fetch the HTML from
 	if v, err := attrs.String("url"); err != nil || v == "" {
 		return errors.New("url is expected to be non-empty string")

internal/fetcher/interface.go

@@ -1,3 +1,5 @@
+// Package fetcher contains the implementations of fetchers to retrieve
+// current versions for the catalog entries
 package fetcher
 
 import (
@@ -12,15 +14,21 @@ import (
 )
 
 type (
+	// Fetcher defines the interface all fetchers have to follow
 	Fetcher interface {
+		// FetchVersion retrieves the latest version for the catalog entry
 		FetchVersion(ctx context.Context, attrs *fieldcollection.FieldCollection) (string, time.Time, error)
+		// Links retrieves a collection of links for the fetcher
 		Links(attrs *fieldcollection.FieldCollection) []database.CatalogLink
+		// Validate validates the configuration given to the fetcher
 		Validate(attrs *fieldcollection.FieldCollection) error
 	}
+	// Create represents a function to instantiate a Fetcher
 	Create func() Fetcher
 )
 
 var (
+	// ErrNoVersionFound signalizes the fetcher was not able to retrieve a version
 	ErrNoVersionFound = errors.New("no version found")
 
 	availableFetchers     = map[string]Create{}
@@ -34,6 +42,7 @@ func registerFetcher(name string, fn Create) {
 	availableFetchers[name] = fn
 }
 
+// Get retrieves an creation function for the given fetcher name
 func Get(name string) Fetcher {
 	availableFetchersLock.RLock()
 	defer availableFetchersLock.RUnlock()

internal/fetcher/json.go

@@ -3,7 +3,7 @@ package fetcher
 import (
 	"bytes"
 	"context"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"regexp"
 	"time"
@@ -13,6 +13,7 @@ import (
 	"github.com/pkg/errors"
 
 	"github.com/Luzifer/go-latestver/internal/database"
+	"github.com/Luzifer/go-latestver/internal/helpers"
 	"github.com/Luzifer/go_helpers/v2/fieldcollection"
 )
 
@@ -28,11 +29,13 @@ var (
 )
 
 type (
+	// JSONFetcher implements the fetcher interface to retrieve a version from a JSON document
 	JSONFetcher struct{}
 )
 
 func init() { registerFetcher("json", func() Fetcher { return &JSONFetcher{} }) }
 
+// FetchVersion retrieves the latest version for the catalog entry
 func (JSONFetcher) FetchVersion(ctx context.Context, attrs *fieldcollection.FieldCollection) (string, time.Time, error) {
 	var (
 		doc *jsonquery.Node
@@ -55,9 +58,9 @@ func (JSONFetcher) FetchVersion(ctx context.Context, attrs *fieldcollection.Fiel
 		if err != nil {
 			return "", time.Time{}, errors.Wrap(err, "executing request")
 		}
-		defer resp.Body.Close()
+		defer func() { helpers.LogIfErr(resp.Body.Close(), "closing response body after read") }()
 
-		body, err = ioutil.ReadAll(resp.Body)
+		body, err = io.ReadAll(resp.Body)
 		if err != nil {
 			return "", time.Time{}, errors.Wrap(err, "reading response body")
 		}
@@ -101,8 +104,10 @@ func (JSONFetcher) FetchVersion(ctx context.Context, attrs *fieldcollection.Fiel
 	return match[1], time.Now(), nil
 }
 
-func (JSONFetcher) Links(attrs *fieldcollection.FieldCollection) []database.CatalogLink { return nil }
+// Links retrieves a collection of links for the fetcher
+func (JSONFetcher) Links(_ *fieldcollection.FieldCollection) []database.CatalogLink { return nil }
 
+// Validate validates the configuration given to the fetcher
 func (JSONFetcher) Validate(attrs *fieldcollection.FieldCollection) error {
 	// @attr url required string "" URL to fetch the HTML from
 	if v, err := attrs.String("url"); err != nil || v == "" {

internal/fetcher/regex.go

@@ -2,7 +2,7 @@ package fetcher
 
 import (
 	"context"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"regexp"
 	"time"
@@ -10,6 +10,7 @@ import (
 	"github.com/pkg/errors"
 
 	"github.com/Luzifer/go-latestver/internal/database"
+	"github.com/Luzifer/go-latestver/internal/helpers"
 	"github.com/Luzifer/go_helpers/v2/fieldcollection"
 )
 
@@ -24,12 +25,14 @@ const (
 )
 
 type (
+	// RegexFetcher implements the fetcher interface to monitor versions on a web request by regex
 	RegexFetcher struct{}
 )
 
 func init() { registerFetcher("regex", func() Fetcher { return &RegexFetcher{} }) }
 
-func (h RegexFetcher) FetchVersion(ctx context.Context, attrs *fieldcollection.FieldCollection) (string, time.Time, error) {
+// FetchVersion retrieves the latest version for the catalog entry
+func (RegexFetcher) FetchVersion(ctx context.Context, attrs *fieldcollection.FieldCollection) (string, time.Time, error) {
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, attrs.MustString("url", nil), nil)
 	if err != nil {
 		return "", time.Time{}, errors.Wrap(err, "creating request")
@@ -39,13 +42,13 @@ func (h RegexFetcher) FetchVersion(ctx context.Context, attrs *fieldcollection.F
 	if err != nil {
 		return "", time.Time{}, errors.Wrap(err, "executing request")
 	}
-	defer resp.Body.Close()
+	defer func() { helpers.LogIfErr(resp.Body.Close(), "closing response body after read") }()
 
 	if resp.StatusCode >= httpStatus3xx {
 		return "", time.Time{}, errors.Errorf("HTTP status %d", resp.StatusCode)
 	}
 
-	data, err := ioutil.ReadAll(resp.Body)
+	data, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return "", time.Time{}, errors.Wrap(err, "reading response body")
 	}
@@ -62,7 +65,8 @@ func (h RegexFetcher) FetchVersion(ctx context.Context, attrs *fieldcollection.F
 	return matches[1], time.Now(), nil
 }
 
-func (h RegexFetcher) Links(attrs *fieldcollection.FieldCollection) []database.CatalogLink {
+// Links retrieves a collection of links for the fetcher
+func (RegexFetcher) Links(attrs *fieldcollection.FieldCollection) []database.CatalogLink {
 	return []database.CatalogLink{
 		{
 			IconClass: "fas fa-globe",
@@ -72,7 +76,8 @@ func (h RegexFetcher) Links(attrs *fieldcollection.FieldCollection) []database.C
 	}
 }
 
-func (h RegexFetcher) Validate(attrs *fieldcollection.FieldCollection) error {
+// Validate validates the configuration given to the fetcher
+func (RegexFetcher) Validate(attrs *fieldcollection.FieldCollection) error {
 	// @attr url required string "" URL to fetch the content from
 	if v, err := attrs.String("url"); err != nil || v == "" {
 		return errors.New("url is expected to be non-empty string")

internal/helpers/log.go

@@ -0,0 +1,14 @@
+// Package helpers contains helper functions to avoid code duplication
+package helpers
+
+import "github.com/sirupsen/logrus"
+
+// LogIfErr yields a logrus error log line when the given error is
+// not nil
+func LogIfErr(err error, msgTpl string, params ...any) {
+	if err == nil {
+		return
+	}
+
+	logrus.WithError(err).Errorf(msgTpl, params...)
+}

internal/version/constraint.go

@@ -3,6 +3,7 @@ package version
 import "github.com/pkg/errors"
 
 type (
+	// Constraint document how a version update should be handled
 	Constraint struct {
 		AllowDowngrade  bool `yaml:"allow_downgrade"`
 		AllowPrerelease bool `yaml:"allow_prerelease"`
@@ -25,6 +26,8 @@ const (
 	compareResultUpgrade
 )
 
+// ShouldApply checks whether a new version should overwrite the old
+// one given the parameters inside the Constraint
 func (c Constraint) ShouldApply(oldVersion, newVersion string) (bool, error) {
 	if oldVersion == "" && newVersion != "" {
 		// The old version does not exist, the new one does, update it!

internal/version/doc.go

@@ -0,0 +1,3 @@
+// Package version contains parsers and methods to validate
+// versions and version updates
+package version

main.go

@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"github.com/gorilla/mux"
+	"github.com/pkg/errors"
 	"github.com/robfig/cron/v3"
 	log "github.com/sirupsen/logrus"
 
@@ -38,10 +39,25 @@ var (
 	version = "dev"
 )
 
-func initApp() {
+func initApp() error {
 	rconfig.AutoEnv(true)
 	if err := rconfig.ParseAndValidate(&cfg); err != nil {
-		log.Fatalf("Unable to parse commandline options: %s", err)
+		return errors.Wrap(err, "parsing commandline options")
+	}
+
+	l, err := log.ParseLevel(cfg.LogLevel)
+	if err != nil {
+		return errors.Wrap(err, "parsing log-level")
+	}
+	log.SetLevel(l)
+
+	return nil
+}
+
+func main() {
+	var err error
+	if err = initApp(); err != nil {
+		log.WithError(err).Fatal("initializing app")
 	}
 
 	if cfg.VersionAndExit {
@@ -49,18 +65,6 @@ func initApp() {
 		os.Exit(0)
 	}
 
-	if l, err := log.ParseLevel(cfg.LogLevel); err != nil {
-		log.WithError(err).Fatal("Unable to parse log level")
-	} else {
-		log.SetLevel(l)
-	}
-}
-
-func main() {
-	initApp()
-
-	var err error
-
 	if err = configFile.Load(cfg.Config); err != nil {
 		log.WithError(err).Fatal("Unable to load configuration")
 	}
@@ -83,7 +87,9 @@ func main() {
 	}
 
 	scheduler := cron.New()
-	scheduler.AddFunc(fmt.Sprintf("@every %s", schedulerInterval), schedulerRun)
+	if _, err = scheduler.AddFunc(fmt.Sprintf("@every %s", schedulerInterval), schedulerRun); err != nil {
+		log.WithError(err).Fatal("registering cron entry")
+	}
 	scheduler.Start()
 
 	router = mux.NewRouter()
@@ -105,7 +111,13 @@ func main() {
 	handler = httpHelper.GzipHandler(handler)
 	handler = httpHelper.NewHTTPLogHandler(handler)
 
-	if err := http.ListenAndServe(cfg.Listen, handler); err != nil {
+	server := &http.Server{
+		Addr:              cfg.Listen,
+		Handler:           handler,
+		ReadHeaderTimeout: time.Second,
+	}
+
+	if err := server.ListenAndServe(); err != nil {
 		log.WithError(err).Fatal("HTTP server exited unclean")
 	}
 }

scheduler.go

@@ -73,7 +73,6 @@ func checkForUpdates(ce *database.CatalogEntry) error {
 	}
 
 	switch {
-
 	case err != nil:
 		logger.WithError(err).Error("Fetcher caused error, error is stored in entry")
 		cm.Error = err.Error()
@@ -109,7 +108,6 @@ func checkForUpdates(ce *database.CatalogEntry) error {
 
 	default:
 		cm.Error = ""
-
 	}
 
 	cm.LastChecked = ptrTime(time.Now().Truncate(time.Second).UTC())