What causes "could not get dependency %q for %q, %q missing in template" in hashicorp/packer?

Add the referenced datasource block to the template: define `data " " " " { ... }` for the missing name shown in the error

hashicorp/packer · error

could not get dependency %q for %q, %q missing in template

Error message

could not get dependency %q for %q, %q missing in template

What it means

While connecting datasource dependency edges in buildPrereqsDAG, Packer looks up each dependency reference (ds.Dependencies) in the vertex map. The dependency refString (e.g. "data.type.name") resolved from the datasource's interpolation does not correspond to any datasource block defined in the template, so no graph edge can be created and this error is appended. It means a datasource references another datasource that is missing from the template.

Source

Thrown at hcl2template/parser.go:448

	}

	// Connect the vertices together
	//
	// Vertices that don't have dependencies will be connected to the
	// root vertex of the graph
	for _, ds := range cfg.Datasources {
		dsName := fmt.Sprintf("data.%s", ds.Name())

		source := verticesMap[dsName]
		if source == nil {
			err = multierror.Append(err, fmt.Errorf("unable to find source vertex %q for dependency analysis, this is likely a Packer bug", dsName))
			continue
		}

		for _, dep := range ds.Dependencies {
			target := verticesMap[dep.String()]
			if target == nil {
				err = multierror.Append(err, fmt.Errorf("could not get dependency %q for %q, %q missing in template", dep.String(), dsName, dep.String()))
				continue
			}

			retGraph.Connect(dag.BasicEdge(source, target))
		}
	}
	for _, loc := range cfg.LocalBlocks {
		locName := fmt.Sprintf("local.%s", loc.LocalName)

		source := verticesMap[locName]
		if source == nil {
			err = multierror.Append(err, fmt.Errorf("unable to find source vertex %q for dependency analysis, this is likely a Packer bug", locName))
			continue
		}

		for _, dep := range loc.dependencies {
			target := verticesMap[dep.String()]

View on GitHub (pinned to eb36e3c3e4)

Solutions

Add the referenced datasource block to the template: define `data "<type>" "<name>" { ... }` for the missing name shown in the error
Fix typos/mismatches in the reference so it exactly matches the datasource block's type and name labels
Check the datasource is defined in the same source file / template scope that Packer parses for this build
Run `packer init` and `packer validate` to catch undefined references earlier with better diagnostics

Example fix

// before: datasource references an undefined sibling
locals { use = data.amazon-ami.ubunut.id }  // typo
data "amazon-ami" "ubuntu" { ... }
// after
locals { use = data.amazon-ami.ubuntu.id }
data "amazon-ami" "ubuntu" { ... }

Defensive patterns

Strategy: validation

Validate before calling

// Grep the template for data.<type>.<name> references and verify each
// has a matching block:
//   grep -oE 'data\.[a-z0-9_-]+\.[a-z0-9_-]+' *.pkr.hcl | sort -u
// then compare against defined: data "<type>" "<name>" blocks.
// CI gate: packer validate template.pkr.hcl must pass before build.

Try / catch

if err := multierrFromDAG; err != nil {
    for _, e := range err.Errors {
        var missing string
        if n, _ := fmt.Sscanf(e.Error(), "could not get dependency %q", &missing); n == 1 {
            fmt.Printf("define datasource block: data \"<type>\" \"%s\" {{ }}\n", missing)
        }
    }
}

Prevention

Always define a datasource block for every data.<type>.<name> reference
Copy exact names instead of retyping them; names are case-sensitive
Run `packer validate` in CI before `packer build`
When renaming a datasource, grep for all data.<type>.<name> usages first

When it happens

Trigger: A datasource block's arguments interpolate `data.<type>.<name>` where the referenced datasource block does not exist (or its type/name labels don't match exactly) in the same template context; raised during evaluateBuildPrereqs via buildPrereqsDAG before prerequisite evaluation.

Common situations: Typo in the datasource name in an interpolation (e.g. data.amazon-ami.ubuntu vs. defined data.amazon-ami.ubunut); referencing a datasource defined in a different template/file not imported; renaming a datasource block without updating references; case-sensitivity mismatches in names.

Related errors

AI-assisted analysis of hashicorp/packer@eb36e3c3e4 (2026-09-05). Data as JSON: /api/errors/0fae0da744bc7b5f. Report an issue: GitHub.