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Allow flag or file based configuration (#620)
Flags can be provided in a file by using the --config=FILE flag. This file can contain environment variables.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,56 @@ | ||
| // Copyright 2017 Google Inc. All Rights Reserved. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
|
|
||
| package cmd | ||
|
|
||
| import ( | ||
| "errors" | ||
| "flag" | ||
| "io/ioutil" | ||
| "os" | ||
|
|
||
| "bitbucket.org/creachadair/shell" | ||
| ) | ||
|
|
||
| func parseFlags(file string) error { | ||
| args, valid := shell.Split(file) | ||
| if !valid { | ||
| return errors.New("flag file contains unclosed quotations") | ||
| } | ||
| // Expand any environment variables in the args | ||
| for i := range args { | ||
| args[i] = os.ExpandEnv(args[i]) | ||
| } | ||
|
|
||
| if err := flag.CommandLine.Parse(args); err != nil { | ||
| return err | ||
| } | ||
|
|
||
| // Call flag.Parse() again so that command line flags | ||
| // can override flags provided in the provided flag file. | ||
| flag.Parse() | ||
| return nil | ||
| } | ||
|
|
||
| // ParseFlagFile parses a set of flags from a file at the provided | ||
| // path. Re-calls flag.Parse() after parsing the flags in the file | ||
| // so that flags provided on the command line take precedence over | ||
| // flags provided in the file. | ||
| func ParseFlagFile(path string) error { | ||
| file, err := ioutil.ReadFile(path) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| return parseFlags(string(file)) | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,109 @@ | ||
| // Copyright 2017 Google Inc. All Rights Reserved. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
|
|
||
| package cmd | ||
|
|
||
| import ( | ||
| "flag" | ||
| "os" | ||
| "testing" | ||
| ) | ||
|
|
||
| func TestParseFlags(t *testing.T) { | ||
| var a, b string | ||
| flag.StringVar(&a, "a", "", "") | ||
| flag.StringVar(&b, "b", "", "") | ||
|
|
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| flag.CommandLine.Init(os.Args[0], flag.ContinueOnError) | ||
|
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| tests := []struct { | ||
| name string | ||
| contents string | ||
| env map[string]string | ||
| cliArgs []string | ||
| expectedErr string | ||
| expectedA string | ||
| expectedB string | ||
| }{ | ||
| { | ||
| name: "two flags per line", | ||
| contents: "-a one -b two", | ||
| expectedA: "one", | ||
| expectedB: "two", | ||
| }, | ||
| { | ||
| name: "one flag per line", | ||
| contents: "-a one\n-b two", | ||
| expectedA: "one", | ||
| expectedB: "two", | ||
| }, | ||
| { | ||
| name: "one flag per line, with line continuation", | ||
| contents: "-a one \\\n-b two", | ||
| expectedA: "one", | ||
| expectedB: "two", | ||
| }, | ||
| { | ||
| name: "one flag in file, one flag on command-line", | ||
| contents: "-a one", | ||
| cliArgs: []string{"-b", "two"}, | ||
| expectedA: "one", | ||
| expectedB: "two", | ||
| }, | ||
| { | ||
| name: "two flags, one overridden by command-line", | ||
| contents: "-a one\n-b two", | ||
| cliArgs: []string{"-b", "three"}, | ||
| expectedA: "one", | ||
| expectedB: "three", | ||
| }, | ||
| { | ||
| name: "two flags, one using an environment variable", | ||
| contents: "-a one\n-b $TEST_VAR", | ||
| env: map[string]string{"TEST_VAR": "from env"}, | ||
| expectedA: "one", | ||
| expectedB: "from env", | ||
| }, | ||
| { | ||
| name: "three flags, one undefined", | ||
| contents: "-a one -b two -c three", | ||
| expectedErr: "flag provided but not defined: -c", | ||
| }, | ||
| } | ||
|
|
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| initialArgs := os.Args[:] | ||
| for _, tc := range tests { | ||
| a, b = "", "" | ||
| os.Args = append(initialArgs, tc.cliArgs...) | ||
| for k, v := range tc.env { | ||
| if err := os.Setenv(k, v); err != nil { | ||
| t.Errorf("%v: os.SetEnv(%q, %q) = %q", tc.name, k, v, err) | ||
| } | ||
| } | ||
|
|
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| if err := parseFlags(tc.contents); err != nil { | ||
| if err.Error() != tc.expectedErr { | ||
| t.Errorf("%v: parseFlags() = %q, want %q", tc.name, err, tc.expectedErr) | ||
| } | ||
| continue | ||
| } | ||
|
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| if tc.expectedA != a { | ||
| t.Errorf("%v: flag 'a' not properly set: got %q, want %q", tc.name, a, tc.expectedA) | ||
| } | ||
| if tc.expectedB != b { | ||
| t.Errorf("%v: flag 'b' not properly set: got %q, want %q", tc.name, b, tc.expectedB) | ||
| } | ||
| } | ||
| } |
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