Consider moving test code to find ansible-vault (or any) executable to production code

[sleberknight]

The VaultEncryptionHelperIntegrationTest contains code that finds the location of the ansible-vault executable using which. If it does not find it, then it falls back to "well known" locations for macOS (assuming Homebrew installation) and Linux.

In our new environments, ansible-vault is installed via pip, so the location is ~/.pip/bin/ansible-vault. Our existing service code (and specifically the "core service" library) assumes the standard Linux location of /usr/bin/ansible-vault, so the code obviously fails.

Instead, it would be better to use the strategy used in the test, i.e. first try finding it via which and then maybe falling back based on OS like the test does. This could be a static method in VaultEncryptionHelper or maybe in VaultConfiguration.

Further, since using which is a generic thing, maybe we add a which(String command) method to Processes and/or ProcessHelper first, and then add a method inVaultConfiguration to get the path of ansible-vault. e.g.

// ProcessHelper.java:

// This is an instance method for easy mocking in tests
public Optional<String> which(String command) {
    return Processes.which(command);
}


// Processes.java:
// Instead of Optional, could also return a "Result" (i.e. like an "Either" having a value or an error/exception)
public static Optional<String> which(String command) {
    // launch "which <command>" and read result
    try {
        var proc = launch("which", command);
        var stdOutLines = KiwiIO.readLinesFromInputStreamOf(proc);
        return firstIfPresent(stdOutLines);
    } catch (Exception e) {
        LOG.warn("There was an error executing the 'which {}' command", command, e);
        return Optional.empty();
    }
}


// VaultConfiguration.java

// The value returned by this may or may not exist, i.e. if which returns nothing, then the fallback value might not exist either
public static String whichAnsibleVaultOrFallback() {
    var pathOptional =  whichAnsibleVault();
    return pathOptional.orElseGet(VaultConfiguration::ansibleVaultFallbackPath);
}

public static Optional<String> whichAnsibleVault() {
    return Processes.which("ansible-vault");
}

private static String ansibleVaultFallbackPath() {
    // maybe return an Os-dependent fallback like in VaultEncryptionHelperIntegrationTest
    return "/fallback/path/to/ansible-vault";
}

[sleberknight]

Created issues:

• Add "which" method to Processes and ProcessHelpers #945
• Add methods in Ansible Vault utilities to find the ansible-vault executable #946