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In this hands-on tutorial, you’ll learn how to manage key/value pairs in HashiCorp Consul’s K/V store using three methods: the web UI, the CLI, and the HTTP API. We’ll cover adding, querying, and deleting entries, plus best practices for decoding API responses.

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1. Prerequisites

When you first open the UI, the Key/Value section should be empty.

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2. Adding Data via the CLI

Use the consul kv put command to insert entries under the apps/eCommerce prefix. 
# 1. Add the database host
consul kv put apps/eCommerce/database_host customer_db

# 2. Add the database name
consul kv put apps/eCommerce/database billing

# 3. Add the connection string
consul kv put apps/eCommerce/connection_string 'Server=myServerAddress;Database=myDataBase;Uid=myUsername;Pwd=myPassword;'
Each command will return a confirmation similar to: 
Success! Data written to: apps/eCommerce/database_host

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3. Deleting an Entry

If you need to remove a key, use consul kv delete. For example, to delete the connection string: 
consul kv delete apps/eCommerce/connection_string
Successful deletion yields: 
Success! Deleted key: apps/eCommerce/connection_string

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4. Adding Data for the Search Service

Next, create configuration entries for a hypothetical search service: 
# Store the current version
consul kv put apps/search/version 4

# Store the service URL
consul kv put apps/search/url search.service.consul
Refresh the UI to verify new keys under apps → search.
If you don’t see the new entries right away, click the Refresh button in the UI or clear your browser cache.

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5. Querying Data in the CLI

Retrieve a value directly from the CLI: 
consul kv get apps/search/url
Output: 
search.service.consul

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6. Querying Data via the HTTP API

Consul’s HTTP API returns values in Base64. First, inspect the raw JSON: 
curl -s http://127.0.0.1:8500/v1/kv/apps/search/url | jq
Sample response: 
[
  {
    "LockIndex": 0,
    "Key": "apps/search/url",
    "Flags": 0,
    "Value": "c2VhcmNoLnNlcnZpY2UuY29uc3Vs",
    "Namespace": "default",
    "CreateIndex": 2359,
    "ModifyIndex": 2359
  }
]
To decode in one step: 
curl -s http://127.0.0.1:8500/v1/kv/apps/search/url \
  | jq -r '.[0].Value' \
  | base64 --decode
Output: 
search.service.consul
Any application using Consul’s K/V HTTP API must Base64-decode the Value field before use.

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7. Operation Summary

OperationCLI CommandAPI Endpoint
Add Keyconsul kv put <key> <value>POST /v1/kv/:key
Delete Keyconsul kv delete <key>DELETE /v1/kv/:key
Get Key (CLI)consul kv get <key>—
Get Key (API)—GET /v1/kv/:key (Base64-encoded)

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8. Further Reading

You’ve now mastered adding, deleting, and retrieving key/value pairs in Consul using the UI, CLI, and HTTP API. Happy configuring!

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