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Apply config

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Declaratively apply configuration at a RESTCONF data path: read the current config, diff it against the intended JSON, and merge (PATCH) only when they differ. dry_run defaults to true and returns the diff without changing anything.

Script cisco_iosxe Verified
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The script

Submitted by hugo989 Typescript (fetch-only)
Verified 2 hours ago
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//native
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type Change = { path: string; current: any; intended: any }
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// Match a member by its full name, or by its local name when one side carries
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// a module prefix and the other doesn't (RFC 7951 qualifies only the top level
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// and module changes).
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function lookup(obj: { [key: string]: any }, key: string) {
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  if (key in obj) return obj[key]
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  const local = key.split(":").pop()
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  const match = Object.keys(obj).find((k) => k.split(":").pop() === local)
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  return match === undefined ? undefined : obj[match]
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}
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// RFC 7951 encodes 64-bit integers and decimals as strings, so "1500" and 1500
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// are the same value.
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function scalarEqual(a: any, b: any) {
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  return a === b || (a != null && b != null && String(a) === String(b))
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}
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// Collects every place where `intended` is not already present in `current`.
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// Objects compare member by member; a list entry is satisfied when some current
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// entry contains all of its members. Members of `current` that `intended` does
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// not mention are ignored, as a PATCH merge leaves them untouched.
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function diff(intended: any, current: any, at: string, out: Change[]) {
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  if (Array.isArray(intended)) {
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    const entries = Array.isArray(current) ? current : []
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    intended.forEach((item, i) => {
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      if (!entries.some((entry) => diff(item, entry, "", []).length === 0)) {
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        out.push({ path: `${at}[${i}]`, current: null, intended: item })
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      }
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    })
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  } else if (intended !== null && typeof intended === "object") {
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    // A GET on a list entry (interface/Loopback=1) returns a one-entry array.
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    if (Array.isArray(current) && current.length === 1) {
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      current = current[0]
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    }
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    if (
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      current === null ||
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      typeof current !== "object" ||
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      Array.isArray(current)
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    ) {
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      out.push({ path: at || "/", current: current ?? null, intended })
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    } else {
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      for (const [key, value] of Object.entries(intended)) {
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        diff(value, lookup(current, key), `${at}/${key}`, out)
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      }
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    }
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  } else if (!scalarEqual(intended, current)) {
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    out.push({ path: at || "/", current: current ?? null, intended })
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  }
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  return out
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}
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/**
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 * Apply config
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 * Declaratively apply configuration at a RESTCONF data path: read the current config there, diff it against the intended JSON, and merge (PATCH) only when they differ. intended is the RFC 7951 body wrapped in the target node, as a GET of path returns it, e.g. {"Cisco-IOS-XE-native:Loopback": {"name": 100, "description": "x"}} for path Cisco-IOS-XE-native:native/interface/Loopback=100. With dry_run (the default) nothing is changed and the diff is returned.
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 */
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export async function main(
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  auth: RT.CiscoIosxe,
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  path: string,
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  intended: { [key: string]: any },
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  dry_run: boolean = true
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) {
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  const url = new URL(
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    `${auth.base_url.replace(/\/+$/, "")}/restconf/data/${path.replace(/^\/+/, "")}`
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  )
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  const authorization = `Basic ${btoa(`${auth.username}:${auth.password}`)}`
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  const currentResponse = await fetch(url, {
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    headers: {
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      Authorization: authorization,
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      Accept: "application/yang-data+json",
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    },
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  })
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  let current: any = null
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  if (currentResponse.ok) {
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    current = currentResponse.status === 204 ? {} : await currentResponse.json()
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  } else if (currentResponse.status !== 404) {
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    throw new Error(`${currentResponse.status} ${await currentResponse.text()}`)
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  }
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  const changes = diff(intended, current ?? {}, "", [])
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  if (changes.length === 0 || dry_run !== false) {
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    return { changed: changes.length > 0, diff: changes, applied: false }
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  }
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  // PATCH merges into an existing resource; when the path holds no data yet,
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  // PUT creates it (RFC 8040 sections 4.5 and 4.6.1). Leaves that already match
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  // are rewritten with the same value, which changes nothing.
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  const method = current === null ? "PUT" : "PATCH"
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  const response = await fetch(url, {
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    method,
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    headers: {
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      Authorization: authorization,
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      "Content-Type": "application/yang-data+json",
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      Accept: "application/yang-data+json",
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    },
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    body: JSON.stringify(intended),
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  })
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  if (!response.ok) {
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    throw new Error(`${response.status} ${await response.text()}`)
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  }
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  return { changed: true, diff: changes, applied: true, method }
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}
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