Polly: Synthesize speech from the CLI

Part 982 of AWS from Zero. This is lesson 9 in the Polly track.

What we are learning

Use synthesize-speech to work with one focused Polly capability from the terminal. This lesson identifies the required input shape, saves the raw response, and keeps inspection separate from execution.

The AWS CLI operation is aws polly synthesize-speech. Required operation inputs: --output-format (string), --text (string), --voice-id (string). The modeled top-level response contains AudioStream, ContentType, RequestCharacters.

Before you run it

aws sts get-caller-identity
REGION="${AWS_REGION:-ap-south-1}"
OUTPUT_FORMAT="replace-with-output-format"
TEXT="replace-with-text"
VOICE_ID="replace-with-voice-id"
aws polly synthesize-speech help

Use a sandbox account or an approved learning environment. Read the operation help before supplying identifiers, ARNs, network ranges, policy documents, or customer data.

Cost note: Synthesized characters, long-form tasks, and storage or delivery can incur charges.

The command

aws polly synthesize-speech \
  --output-format "$OUTPUT_FORMAT" \
  --text "$TEXT" \
  --voice-id "$VOICE_ID" \
  --region "$REGION" \
  part-982-payload.bin \
  --output json > part-982-response.json

The response is saved to part-982-response.json so inspection is separate from execution. The explicit variables above keep required identifiers visible before the API call.

Inspect the result

node -e "const r=require('./part-982-response.json'); console.log(JSON.stringify(r, null, 2))"
wc -c part-982-payload.bin

Compare the returned identifiers and status fields with the account, Region, and resource you intended to target. For asynchronous operations, continue with the service's matching get, list, or describe command until it reaches a terminal state.

One tiny variation

node -e "const fs=require('node:fs'); const b=fs.readFileSync('part-982-payload.bin'); console.log({bytes:b.length})"

This variation changes output inspection rather than adding another infrastructure concept. Keep the raw JSON while developing a query so a narrow projection does not hide an error or unexpected field.

Common mistake

Do not treat a zero exit code as proof that the intended state is active everywhere. AWS control planes can be eventually consistent, and some operations start asynchronous work.

Cleanup

# This operation is read-only, operational, or needs resource-specific rollback.
# Re-read the command output before changing shared infrastructure.
rm -f part-982-request.json part-982-response.json part-982-payload.bin part-982-debug.log

Local request and response files may contain account IDs, ARNs, names, or service configuration. Remove them when the lab is complete and follow dependency-aware cleanup for any AWS resource you created.

Next, we will learn Rekognition: Describe collection from the CLI.

Official AWS CLI reference