Merge 4ee2049 into f699d03

.gitignore

@@ -1,4 +1,5 @@
 /.idea/
+.history
 /coverage/
 node_modules/
 *.log

.travis.yml

@@ -1,6 +1,8 @@
 language: node_js
 node_js:
   - node
+  - 16
+  - 14
   - 12
   - 10
   - 8

Dockerfiles/build/files/public/index.html

@@ -10,6 +10,7 @@ <h3>
 </h3>
 <h3>
   Yup, this container runs on Node.js version ${ NODE_VERSION }
+  And this is a splendid variable with default value "${ NODE_VERSION:-duck }"
 </h3>
 </body>
 </html>

Dockerfiles/run/files/public/index.html

@@ -10,6 +10,7 @@ <h3>
 </h3>
 <h3>
   Yup, this container runs on Node.js version ${ NODE_VERSION }
+  And this is a splendid variable with default value "${ NODE_VERSION:-duck }"
 </h3>
 </body>
 </html>

README.md

@@ -172,6 +172,45 @@ export MYVAR4=hello  # same as --env MYVAR4=hello
 >
 > However, because the --system flag is set, the system environment variable value 'bar' is preferred.
 
+<br><br>
+
+#### **envsub variable placeholder default values**
+
+**For the `dollar-curly` syntax only**, defining default values is possible.
+The syntax is the following:
+```yaml
+# Before substitution
+Variable with default value: ${VARIABLE_NAME:-default}.
+# After substitution
+Variable with default value: default.
+
+# Before substitution
+Variable with default value + whitespaces: ${VARIABLE_NAME:-        default value }.
+# After substitution
+Variable with default value + whitespaces:         default value .
+```
+
+##### Without modifier flags
+
+**By default**, every `variable placeholder with default value` is substituted even if not set by the environment or from the cli.
+
+![envsub templateFile outputFile](./images/envsub-default-normal.png "envsub templateFile outputFile")
+
+---
+##### With --env or --env-file
+When using the **--env** and **--env-file** flags, only the restricted `variable placeholders with default value` are substituted even if not set by the environment or from the cli.
+
+![envsub --env MYVAR1=llama --all templateFile outputFile](./images/envsub-default-env.png "envsub --env MYVAR1=llama --all templateFile outputFile")
+
+---
+
+##### With --env or --env-file and --all
+
+- When using the **--env** and **--env-file** flags with the **--all** flag, every `variable placeholder with default value` is substituted even if not set by the environment or from the cli.
+
+![envsub --env MYVAR1=llama --env MYVAR3 templateFile outputFile](./images/envsub-default-env-all.png "envsub --env MYVAR1=llama --env MYVAR3 templateFile outputFile")
+
+
 <br><br>
 
 #### **envsub overwrite** .. ```envsub templateFile```
@@ -216,7 +255,7 @@ envsub --help
 
     -h, --help                output usage information
     -V, --version             output the version number
-    -a, --all                 substitute all system environment variables - avoids substitution restrictions when using the --env or --env-file flags
+    -a, --all                 substitute all system environment variables and all variable placeholders with default value (only for dollar-curly syntax, like ${VAR_NAME:-default value}) - avoids substitution restrictions when using the --env or --env-file flags
     -d, --diff                show diff between template file and output file
     -e, --env <name>[=value]  environment variable to substitute .. if none specified then substitute all (but see --env-file) .. this flag can be repeated
     -f, --env-file <envFile>  load environment variables from an .env file .. this flag can be repeated

bin/envsub.js

@@ -21,7 +21,7 @@ let addEnvironmentVariableFile = (envVarFile, envVarFileList) => {
 program
   .version(version)
   .usage('[options] <templateFile> [outputFile]')
-  .option('-a, --all', 'substitute all system environment variables - avoids substitution restrictions when using the --env or --env-file flags')
+  .option('-a, --all', 'substitute all system environment variables and all variable placeholders with default value (only for dollar-curly syntax, like ${VAR_NAME:-default value}) - avoids substitution restrictions when using the --env or --env-file flags')
   .option('-d, --diff', 'show diff between template file and output file')
   .option('-e, --env <name>[=value]', 'environment variable to substitute .. if none specified then substitute all (but see --env-file) .. this flag can be repeated', addEnvironmentVariable, [])
   .option('-f, --env-file <envFile>', 'load environment variables from an .env file .. this flag can be repeated', addEnvironmentVariableFile, [])

js/envsub-parser.js

@@ -1,41 +1,55 @@
 const config = require('../main.config');
+const matchAll = require('string.prototype.matchall');
 const DotEnvParser = require('./DotEnvParser');
-const DEFAULT_SYNTAX = 'dollar-curly';
+
+matchAll.shim(); // will be a no-op if not needed
+
+const SYNTAX = {
+  DOLLAR_BASIC: 'dollar-basic',
+  DOLLAR_CURLY: 'dollar-curly',
+  DOLLAR_BOTH: 'dollar-both',
+  HANDLEBARS: 'handlebars'
+};
 
 let dynamicRegexes = (opts) => {
 
-  let regexObj = (lhs, cleanLhs, rhs, sep) => {
-    return {lhs, cleanLhs, rhs, sep};
+  let regexObj = (lhs, cleanLhs, rhs, sep, type) => {
+    return {lhs, cleanLhs, rhs, sep, type};
   };
 
   let dynamicRegexes = [];
 
   if (opts.syntax === 'default') {
-    opts.syntax = DEFAULT_SYNTAX;
+    opts.syntax = SYNTAX.DOLLAR_CURLY;
   }
 
-  if (opts.syntax === 'dollar-basic' || opts.syntax === 'dollar-both') {
-    dynamicRegexes.push(regexObj('\\$', '$', '', ''));
+  if (opts.syntax === SYNTAX.DOLLAR_BASIC || opts.syntax === SYNTAX.DOLLAR_BOTH) {
+    dynamicRegexes.push(regexObj('\\$', '$', '', '', opts.syntax));
   }
 
-  if (opts.syntax === 'dollar-curly' || opts.syntax === 'dollar-both') {
-    dynamicRegexes.push(regexObj('\\${', '${', '}', ' *'));
+  if (opts.syntax === SYNTAX.DOLLAR_CURLY || opts.syntax === SYNTAX.DOLLAR_BOTH) {
+    dynamicRegexes.push(regexObj('\\${', '${', '}', ' *', opts.syntax));
   }
 
-  if (opts.syntax === 'handlebars') {
-    dynamicRegexes.push(regexObj('{{', '{{', '}}', ' *'));
+  if (opts.syntax === SYNTAX.HANDLEBARS) {
+    dynamicRegexes.push(regexObj('{{', '{{', '}}', ' *', opts.syntax));
   }
 
   return dynamicRegexes;
 };
 
-let substitute = (matches, contents, opts, dRegex) => {
+let substitute = (matches, contents, opts) => {
 
-  matches && matches.forEach((match) => {
-    let envVarName = match.replace(dRegex.cleanLhs, '').replace(dRegex.rhs, '').trim();
+  matches && matches.forEach(([match, envVarName, defaultValue]) => {
     let envVarValue = process.env[envVarName];
     if (envVarValue || !opts.protect) {
-      contents = contents.replace(match, envVarValue || '');
+      if (envVarValue !== undefined) {
+        contents = contents.replace(match, envVarValue);
+      } else if (defaultValue !== undefined) {
+        contents = contents.replace(match, defaultValue);
+      } else {
+        contents = contents.replace(match, '');
+      }
     }
   });
   return contents;
@@ -53,30 +67,49 @@ let envsubParser = (contents, args) => {
 
     if (!opts.envs.length) {
 
-      // Find all env var matches
-      let regexp = `${dRegex.lhs}${dRegex.sep}${config.regex}${dRegex.sep}${dRegex.rhs}`;
-      let matches = contents.match(new RegExp(regexp, 'g'));
+      // Find all env var matches      
+      const regexp = dRegex.type === SYNTAX.DOLLAR_CURLY ? 
+        // default value support is only available with dollar-curly syntax
+        [ dRegex.lhs, dRegex.sep, config.curlyRegex(false), dRegex.sep, dRegex.rhs ].join('') :
+        // Fallback to everything else
+        [ dRegex.lhs, dRegex.sep, `(${config.regex})`,      dRegex.sep, dRegex.rhs].join('');
+
+      let matches = contents.matchAll(new RegExp(regexp, 'g'));
+      matches = [...matches].map(([match, envVarName, defaultValue]) => [match, envVarName, defaultValue]);
 
       // Substitute
       contents = substitute(matches, contents, opts, dRegex);
 
     } else {
 
+      // Iterate over selected env variables
       opts.envs.forEach((env) => {
-
+        
         if (opts.system && process.env[env.name] == null || !opts.system) {
           if (env.value != null) {
             process.env[env.name] = env.value;
           }
         }
 
-        let regexp = `${dRegex.lhs}${dRegex.sep}${env.name}${dRegex.sep}${dRegex.rhs}`;
-        let matches = contents.match(new RegExp(regexp, 'g'));
-
+        let regexp = dRegex.type === SYNTAX.HANDLEBARS ?
+          [ dRegex.lhs, dRegex.sep, `(${env.name})`,                    dRegex.sep, dRegex.rhs ].join('') : 
+          [ dRegex.lhs, dRegex.sep, config.curlyRegex(false, env.name), dRegex.sep, dRegex.rhs ].join('');
+        let matches = contents.matchAll(new RegExp(regexp, 'g'));
+        matches = [...matches].map(([match, envVarName, defaultValue]) => [match, envVarName, defaultValue]);
+
         // Substitute
         contents = substitute(matches, contents, opts, dRegex);
-
       });
+
+      // In case of all flag we want to replace the ones with default value set
+      if (opts.all && dRegex.type === SYNTAX.DOLLAR_CURLY) {
+        let regexp = [ dRegex.lhs, dRegex.sep, config.curlyRegex(true), dRegex.sep, dRegex.rhs ].join('');
+        let matches = contents.matchAll(new RegExp(regexp, 'g'));
+        matches = [...matches].map(([match, envVarName, defaultValue]) => [match, envVarName, defaultValue]);
+
+        // Substitute
+        contents = substitute(matches, contents, opts, dRegex);
+      }
     }
   });
 

main.config.js

@@ -1,3 +1,4 @@
+const VARIABLE_NAME_REGEX = '[a-zA-Z_]+[a-zA-Z0-9_]*';
 const config = {
   envsub: {
     DEFAULT_OPTIONS: {
@@ -12,7 +13,14 @@ const config = {
       diff: false
     }
   },
-  regex: '[a-zA-Z_]+[a-zA-Z0-9_]*'
+  regex: VARIABLE_NAME_REGEX,
+  curlyRegex: (mustHaveDefaultValue, variableNameRegex = VARIABLE_NAME_REGEX) => {
+    const separatorRegex = ':-';
+    const variableValueRegex = '[^}]*';
+    const optionalDefaultValueModifier = mustHaveDefaultValue ? '' : '?';
+
+    return `(${variableNameRegex})(?:${separatorRegex}(?<=${separatorRegex})(${variableValueRegex}))${optionalDefaultValueModifier}`;
+  }
 };
 
 module.exports = config;