diff options
| -rw-r--r-- | context/context.go | 63 |
1 files changed, 52 insertions, 11 deletions
diff --git a/context/context.go b/context/context.go index 321d4fa42c..49de7f4695 100644 --- a/context/context.go +++ b/context/context.go @@ -88,7 +88,9 @@ func LoadContext(filename string, explicitVars *[]string) (*Context, error) { return nil, contextLoadingError(filename, err) } - // Merge variables (explicit > import > include > global > default) + // Merge variables defined at different levels. The + // `mergeContextValues` function is documented with the merge + // hierarchy. ctx.ResourceSets = ctx.mergeContextValues() if err != nil { @@ -163,14 +165,50 @@ func flattenPrepareResourceSetPaths(rs *[]ResourceSet) []ResourceSet { // Merges the context and resource set variables according in the // desired precedence order. +// +// For now the reasoning behind the merge order is from least specific +// in relation to the cluster configuration, which means that the +// precedence is (in ascending order): +// +// 1. Default values in resource sets. +// 2. Values imported from files (via `import:`) +// 3. Global values in a cluster configuration +// 4. Values set in a resource set's `include`-section +// 5. Explicit values set on the CLI (`--var`) +// +// For a discussion on the reasoning behind this order, please consult +// https://github.com/tazjin/kontemplate/issues/142 func (ctx *Context) mergeContextValues() []ResourceSet { updated := make([]ResourceSet, len(ctx.ResourceSets)) + // Merging has to happen separately for every individual + // resource set to make use of the default values: for i, rs := range ctx.ResourceSets { - merged := loadDefaultValues(&rs, ctx) + // Begin by loading default values from the resource + // sets configuration. + // + // Resource sets are used across different cluster + // contexts and the default values in them have the + // lowest precedence. + defaultValues := loadDefaultValues(&rs, ctx) + + // Continue by merging default values with values + // imported from external files. Those values are also + // used across cluster contexts, but have higher + // precedence than defaults. + merged := util.Merge(defaultValues, &ctx.ImportedVars) + + // Merge global values defined in the cluster context: merged = util.Merge(merged, &ctx.Global) - merged = util.Merge(merged, &ctx.ImportedVars) + + // Merge values configured in the resource set's + // `include` section: + merged = util.Merge(merged, &rs.Values) + + // Merge values defined explicitly on the CLI: merged = util.Merge(merged, &ctx.ExplicitVars) + + // Continue with the newly merged resource set: rs.Values = *merged updated[i] = rs } @@ -178,23 +216,26 @@ func (ctx *Context) mergeContextValues() []ResourceSet { return updated } -// Loads and merges default values for a resource set collection from path/to/set/default.{json|yaml}. -// YAML takes precedence over JSON. -// Default values in resource set collections have the lowest priority possible. +// Loads default values for a resource set collection from +// path/to/set/default.{json|yaml}. func loadDefaultValues(rs *ResourceSet, c *Context) *map[string]interface{} { var defaultVars map[string]interface{} for _, filename := range util.DefaultFilenames { err := util.LoadData(path.Join(c.BaseDir, rs.Path, filename), &defaultVars) if err == nil { - return util.Merge(&defaultVars, &rs.Values) + return &defaultVars } } - // The actual error is not inspected here. The reasoning for this is that in case of serious problems (e.g. - // permission issues with the folder / folder not existing) failure will occur a bit later anyways. - // Otherwise we'd have to differentiate between file-not-found-errors (no default values specified) and other - // errors here. + // The actual error is not inspected here. The reasoning for + // this is that in case of serious problems (e.g. permission + // issues with the folder / folder not existing) failure will + // occur a bit later anyways. + // + // Otherwise we'd have to differentiate between + // file-not-found-errors (no default values specified) and + // other errors here. return &rs.Values } |