Elasticsearch#

All Elasticsearch interaction is via REST API using curl. No SDK or client library required.

Authentication#

Every request needs the cluster URL and an API key:

bash

# Set these for your session (or export in .env / shell profile)
ES_URL="https://your-cluster.es.cloud.elastic.co:443"
ES_API_KEY="your-base64-api-key"

# All requests follow this pattern:
curl -s "${ES_URL%/}/<endpoint>" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" \
  -H "Content-Type: application/json" \
  -d '<json-body>'

API key format: Base64-encoded id:api_key string. Pass as-is in the Authorization: ApiKey header.

If the user provides a URL and key, export them as ES_URL and ES_API_KEY before running commands.

Important — variable expansion in curl:

• Always use $(printenv ES_API_KEY) instead of $ES_API_KEY in curl headers. The $ES_API_KEY variable may not expand correctly in the shell, resulting in empty Authorization headers and 401 errors.
• Always use ${ES_URL%/} to strip any trailing slash from the URL, preventing double-slash path issues (e.g., //_cluster/health).

Quick Health Check#

bash

# Cluster health (green/yellow/red) — NOT available on serverless
curl -s "${ES_URL%/}/_cluster/health" -H "Authorization: ApiKey $(printenv ES_API_KEY)" | jq .

# Node stats summary — NOT available on serverless
curl -s "${ES_URL%/}/_cat/nodes?v&h=name,heap.percent,ram.percent,cpu,load_1m,disk.used_percent"  \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)"

# Index overview (works on both serverless and traditional)
curl -s "${ES_URL%/}/_cat/indices?v&s=store.size:desc&h=index,health,status,docs.count,store.size" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)"

Serverless Elasticsearch: If you get api_not_available_exception errors, the cluster is running in serverless mode. The following APIs are not available in serverless:

• _cluster/health, _cluster/settings, _cluster/allocation/explain, _cluster/pending_tasks
• _cat/nodes, _cat/shards
• _nodes/hot_threads, _nodes/stats
• ILM APIs ( _ilm/*)

Use _cat/indices and _search APIs as the starting point instead — these work everywhere.

Search (Query DSL)#

bash

# Simple match query
curl -s "${ES_URL%/}/my-index/_search" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" \
  -H "Content-Type: application/json" \
  -d '{
    "query": { "match": { "message": "error timeout" } },
    "size": 10
  }' | jq .

# Bool query (must + filter + must_not)
curl -s "${ES_URL%/}/my-index/_search" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" \
  -H "Content-Type: application/json" \
  -d '{
    "query": {
      "bool": {
        "must": [ { "match": { "message": "error" } } ],
        "filter": [ { "range": { "@timestamp": { "gte": "now-1h" } } } ],
        "must_not": [ { "term": { "level": "debug" } } ]
      }
    },
    "size": 20,
    "sort": [ { "@timestamp": { "order": "desc" } } ]
  }' | jq .

For full Query DSL reference (term, terms, range, wildcard, regexp, nested, exists, multi_match, etc.), see references/query-dsl.md.

Index & Document Operations#

bash

# Create index with mappings
curl -s -X PUT "${ES_URL%/}/my-index" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" \
  -H "Content-Type: application/json" \
  -d '{
    "settings": { "number_of_shards": 1, "number_of_replicas": 1 },
    "mappings": {
      "properties": {
        "message":    { "type": "text" },
        "@timestamp": { "type": "date" },
        "level":      { "type": "keyword" },
        "count":      { "type": "integer" }
      }
    }
  }'

# Index a document (auto-generate ID)
curl -s -X POST "${ES_URL%/}/my-index/_doc" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" \
  -H "Content-Type: application/json" \
  -d '{ "message": "hello world", "@timestamp": "2026-01-31T12:00:00Z", "level": "info" }'

# Index with specific ID
curl -s -X PUT "${ES_URL%/}/my-index/_doc/doc-123" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" \
  -H "Content-Type: application/json" \
  -d '{ "message": "specific doc", "level": "warn" }'

# Get document
curl -s "${ES_URL%/}/my-index/_doc/doc-123" -H "Authorization: ApiKey $(printenv ES_API_KEY)" | jq .

# Update document (partial)
curl -s -X POST "${ES_URL%/}/my-index/_update/doc-123" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" \
  -H "Content-Type: application/json" \
  -d '{ "doc": { "level": "error" } }'

# Delete document
curl -s -X DELETE "${ES_URL%/}/my-index/_doc/doc-123" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)"

# Bulk operations (newline-delimited JSON)
curl -s -X POST "${ES_URL%/}/_bulk" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" \
  -H "Content-Type: application/x-ndjson" \
  --data-binary @- << 'EOF'
{"index":{"_index":"my-index"}}
{"message":"bulk doc 1","level":"info","@timestamp":"2026-01-31T12:00:00Z"}
{"index":{"_index":"my-index"}}
{"message":"bulk doc 2","level":"warn","@timestamp":"2026-01-31T12:01:00Z"}
EOF

Aggregations#

bash

# Terms aggregation (top values)
curl -s "${ES_URL%/}/my-index/_search?size=0" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" \
  -H "Content-Type: application/json" \
  -d '{
    "aggs": {
      "levels": { "terms": { "field": "level", "size": 10 } }
    }
  }' | jq '.aggregations'

# Date histogram + nested metric
curl -s "${ES_URL%/}/my-index/_search?size=0" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" \
  -H "Content-Type: application/json" \
  -d '{
    "query": { "range": { "@timestamp": { "gte": "now-24h" } } },
    "aggs": {
      "over_time": {
        "date_histogram": { "field": "@timestamp", "fixed_interval": "1h" },
        "aggs": {
          "avg_count": { "avg": { "field": "count" } }
        }
      }
    }
  }' | jq '.aggregations'

For more aggregation types (cardinality, percentiles, composite, filters, significant_terms, etc.), see references/aggregations.md.

Mappings & Index Management#

bash

# Get mapping
curl -s "${ES_URL%/}/my-index/_mapping" -H "Authorization: ApiKey $(printenv ES_API_KEY)" | jq .

# Add field to existing mapping (mappings are additive — you can't change existing field types)
curl -s -X PUT "${ES_URL%/}/my-index/_mapping" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" \
  -H "Content-Type: application/json" \
  -d '{ "properties": { "new_field": { "type": "keyword" } } }'

# Reindex (change mappings, rename index, etc.)
curl -s -X POST "${ES_URL%/}/_reindex" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" \
  -H "Content-Type: application/json" \
  -d '{
    "source": { "index": "old-index" },
    "dest":   { "index": "new-index" }
  }'

# Delete index
curl -s -X DELETE "${ES_URL%/}/my-index" -H "Authorization: ApiKey $(printenv ES_API_KEY)"

# Index aliases
curl -s -X POST "${ES_URL%/}/_aliases" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" \
  -H "Content-Type: application/json" \
  -d '{
    "actions": [
      { "add": { "index": "my-index-v2", "alias": "my-index" } },
      { "remove": { "index": "my-index-v1", "alias": "my-index" } }
    ]
  }'

# Index templates (for time-series / rollover patterns)
curl -s -X PUT "${ES_URL%/}/_index_template/my-template" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" \
  -H "Content-Type: application/json" \
  -d '{
    "index_patterns": ["logs-*"],
    "template": {
      "settings": { "number_of_shards": 1 },
      "mappings": {
        "properties": {
          "message":    { "type": "text" },
          "@timestamp": { "type": "date" }
        }
      }
    }
  }'

Cluster & Troubleshooting#

Note: Most APIs in this section are not available on serverless Elasticsearch. They only work on self-managed or traditional Elastic Cloud deployments.

bash

# Allocation explanation (why is a shard unassigned?) — NOT serverless
curl -s "${ES_URL%/}/_cluster/allocation/explain" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" \
  -H "Content-Type: application/json" \
  -d '{ "index": "my-index", "shard": 0, "primary": true }' | jq .

# Pending tasks
curl -s "${ES_URL%/}/_cluster/pending_tasks" -H "Authorization: ApiKey $(printenv ES_API_KEY)" | jq .

# Hot threads (performance debugging)
curl -s "${ES_URL%/}/_nodes/hot_threads" -H "Authorization: ApiKey $(printenv ES_API_KEY)"

# Shard allocation
curl -s "${ES_URL%/}/_cat/shards?v&s=store:desc&h=index,shard,prirep,state,docs,store,node" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)"

# Task management (long-running operations)
curl -s "${ES_URL%/}/_tasks?actions=*search&detailed" -H "Authorization: ApiKey $(printenv ES_API_KEY)" | jq .

# Cluster settings (persistent + transient)
curl -s "${ES_URL%/}/_cluster/settings?include_defaults=false" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" | jq .

For Kibana API operations (dashboards, data views, saved objects, alerting rules), see references/kibana-api.md.

Data Streams & ILM#

Note: ILM APIs ( _ilm/*) are not available on serverless. Data stream listing works on both.

bash

# List data streams
curl -s "${ES_URL%/}/_data_stream" -H "Authorization: ApiKey $(printenv ES_API_KEY)" | jq .

# Create ILM policy
curl -s -X PUT "${ES_URL%/}/_ilm/policy/my-policy" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" \
  -H "Content-Type: application/json" \
  -d '{
    "policy": {
      "phases": {
        "hot":    { "actions": { "rollover": { "max_age": "7d", "max_size": "50gb" } } },
        "warm":   { "min_age": "30d", "actions": { "shrink": { "number_of_shards": 1 } } },
        "delete": { "min_age": "90d", "actions": { "delete": {} } }
      }
    }
  }'

# Check ILM status for an index
curl -s "${ES_URL%/}/my-index/_ilm/explain" -H "Authorization: ApiKey $(printenv ES_API_KEY)" | jq .

ES|QL (Elasticsearch Query Language)#

For Elasticsearch 8.11+, ES|QL offers a pipe-based query syntax:

bash

curl -s -X POST "${ES_URL%/}/_query" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" \
  -H "Content-Type: application/json" \
  -d '{
    "query": "FROM logs-* | WHERE level == \"error\" | STATS count = COUNT(*) BY service.name | SORT count DESC | LIMIT 10"
  }' | jq .

For querying OpenTelemetry data (OTEL logs, traces, metrics, correlation patterns), see references/otel-data.md.

Ingest Pipelines#

bash

# Create pipeline
curl -s -X PUT "${ES_URL%/}/_ingest/pipeline/my-pipeline" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" \
  -H "Content-Type: application/json" \
  -d '{
    "processors": [
      { "grok": { "field": "message", "patterns": ["%{TIMESTAMP_ISO8601:timestamp} %{LOGLEVEL:level} %{GREEDYDATA:msg}"] } },
      { "date": { "field": "timestamp", "formats": ["ISO8601"] } },
      { "remove": { "field": "timestamp" } }
    ]
  }'

# Test pipeline
curl -s -X POST "${ES_URL%/}/_ingest/pipeline/my-pipeline/_simulate" \
  -H "Authorization: ApiKey $(printenv ES_API_KEY)" \
  -H "Content-Type: application/json" \
  -d '{
    "docs": [
      { "_source": { "message": "2026-01-31T12:00:00Z ERROR something broke" } }
    ]
  }' | jq .

Tips#

• Always use jq to format JSON output — Elasticsearch responses are verbose.
• ?size=0 on search requests when you only want aggregations (skip hits).
• _cat APIs ( _cat/indices, _cat/shards, _cat/nodes) give human-readable tabular output — add ?v for headers, ?format=json for JSON.
• Scroll/PIT for large exports — don't use from/ size beyond 10,000 hits. Use search_after + PIT instead.
• Field types matter — keyword for exact match/aggs, text for full-text search. Check mappings before querying.
• Date math in index names — logs-{now/d} resolves to today's date. Useful for time-based indices.