xt3r4m · October 21, 2022 14:00 · Mar 21, 2017 · Mar 21, 2017 · Dec 4, 2016 · Dec 4, 2016
diff --git a/kubectl.md b/kubectl.md
@@ -87,8 +87,7 @@ If we do not wish to use `jq` (or have no access to `jq`) need filtering and pow
 we may use Kubectl's built-in support for golang templates (inline or from a template file on disk):
 
 ```
-kubectl get no -o go-template='{{range .items}}{{if .spec.unschedulable}}{{.metadata.name}} {{.spec.externalID}}{{"\n"}}{{end}}{{e
-nd}}'
+kubectl get no -o go-template='{{range .items}}{{if .spec.unschedulable}}{{.metadata.name}} {{.spec.externalID}}{{"\n"}}{{end}}{{end}}'
 or
 kubectl get no -o go-template="{{range .items}}{{if .spec.unschedulable}}{{.metadata.name}} {{.spec.externalID}}:{{end}}{{end}}" | tr ":" "\n"
 ```

diff --git a/kubectl.md b/kubectl.md
@@ -87,6 +87,9 @@ If we do not wish to use `jq` (or have no access to `jq`) need filtering and pow
 we may use Kubectl's built-in support for golang templates (inline or from a template file on disk):
 
 ```
+kubectl get no -o go-template='{{range .items}}{{if .spec.unschedulable}}{{.metadata.name}} {{.spec.externalID}}{{"\n"}}{{end}}{{e
+nd}}'
+or
 kubectl get no -o go-template="{{range .items}}{{if .spec.unschedulable}}{{.metadata.name}} {{.spec.externalID}}:{{end}}{{end}}" | tr ":" "\n"
 ```
 

diff --git a/kubectl.md b/kubectl.md
@@ -19,7 +19,7 @@ kubectl get po -o wide
 ## Json and Jq
 
 I've found the internal data structures easier to explore using the `-o json` output with [jid](https://github.com/simeji/jid) 
-and [jq](https://stedolan.github.io/jq].
+and [jq](https://stedolan.github.io/jq).
 
 Once both `jq` and `jid` are installed (assuming OSX), we can quickly discover the data with the following command:
 

diff --git a/kubectl.md b/kubectl.md
@@ -112,4 +112,4 @@ kubectl get no -o jsonpath="{range.items[?(@.spec.unschedulable)]}{.metadata.nam
 ```
 
 More examples of using jsonpath can be found in 
-[the Kubernetes tests for the JSONPath utility](https://github.com/kubernetes/kubernetes/blob/v1.5.0-beta.2/pkg/util/jsonpath/jsonpath_test.go#L149): 
+[the Kubernetes tests for the JSONPath utility](https://github.com/kubernetes/kubernetes/blob/v1.5.0-beta.2/pkg/util/jsonpath/jsonpath_test.go#L149)
diff --git a/kubectl.md b/kubectl.md
@@ -29,7 +29,7 @@ kubectl get no -o json | jid -q | pbcopy
 
 This allows us to explore the json data interactively and keep our final `jq` query on the clipboard:
 
-[![asciicast](https://asciinema.org/a/cpazej888znujgm04ewzsv0mk)](https://asciinema.org/a/cpazej888znujgm04ewzsv0mk)
+[![asciicast](https://asciinema.org/a/cpazej888znujgm04ewzsv0mk.png)](https://asciinema.org/a/cpazej888znujgm04ewzsv0mk)
 
 **note**: `jid` currently implements it's own query parser to allow powerfull autocompletion, the drawback is
 a lack of support for all the `jq` constructs (i.e.: we have to specify an index for array elements during discovery).
@@ -47,7 +47,7 @@ kubectl get no -o json | jq -r '[.items[] | {name:.metadata.name, id:.spec.exter
 ```
 
 Here is how the above query was built up using `jid` and `jq`:
-[![asciicast](https://asciinema.org/a/egmrydi963o31232sry4bfscf)](https://asciinema.org/a/egmrydi963o31232sry4bfscf)
+[![asciicast](https://asciinema.org/a/egmrydi963o31232sry4bfscf.png)](https://asciinema.org/a/egmrydi963o31232sry4bfscf)
 
 Converting the json array into a tabular output with `jq` can be done using `@tsv` as follows:
 
@@ -71,7 +71,7 @@ kubectl get po -o wide --sort-by=.spec.nodeName
 ```
 
 Using `jid` to list pods sorted by node:
-[![asciicast](https://asciinema.org/a/36q5fxao2l8lta6ztf9akqciq)](https://asciinema.org/a/36q5fxao2l8lta6ztf9akqciq)
+[![asciicast](https://asciinema.org/a/36q5fxao2l8lta6ztf9akqciq.png)](https://asciinema.org/a/36q5fxao2l8lta6ztf9akqciq)
 
 The usage of Custom Columns with the knowledge of the data structure gained from `jid`, is also much easier:
 

diff --git a/kubectl.md b/kubectl.md
@@ -0,0 +1,115 @@
+# Kubectl output options
+
+Let's look at some basic kubectl output options. 
+
+Our intention is to list nodes (with their AWS InstanceId) and Pods (sorted by node).
+
+We can start with:
+
+```
+kubectl get no
+```
+
+and 
+
+```
+kubectl get po -o wide
+```
+
+## Json and Jq
+
+I've found the internal data structures easier to explore using the `-o json` output with [jid](https://github.com/simeji/jid) 
+and [jq](https://stedolan.github.io/jq].
+
+Once both `jq` and `jid` are installed (assuming OSX), we can quickly discover the data with the following command:
+
+```
+kubectl get no -o json | jid -q | pbcopy
+```
+
+This allows us to explore the json data interactively and keep our final `jq` query on the clipboard:
+
+[![asciicast](https://asciinema.org/a/cpazej888znujgm04ewzsv0mk)](https://asciinema.org/a/cpazej888znujgm04ewzsv0mk)
+
+**note**: `jid` currently implements it's own query parser to allow powerfull autocompletion, the drawback is
+a lack of support for all the `jq` constructs (i.e.: we have to specify an index for array elements during discovery).
+
+As can be seen in the recording: 
+once done with `jid`, getting rid of the index on the `items` array in `jq`, did gave us the full listing.
+
+`jq` gives us a lot more power for example:
+
+Boxing the result into it's own array and constructing a new object combining
+several nested attributes gives us the following query:
+
+```
+kubectl get no -o json | jq -r '[.items[] | {name:.metadata.name, id:.spec.externalID, unschedulable:.spec.unschedulable}]'
+```
+
+Here is how the above query was built up using `jid` and `jq`:
+[![asciicast](https://asciinema.org/a/egmrydi963o31232sry4bfscf)](https://asciinema.org/a/egmrydi963o31232sry4bfscf)
+
+Converting the json array into a tabular output with `jq` can be done using `@tsv` as follows:
+
+```
+kubectl get no -o json | jq -r '.items[] | select(.spec.unschedulable!=true) | [.metadata.name,.spec.externalID] | @tsv'
+```
+
+Jq also allows us to sort:
+
+```
+kubectl get po -o json | jq -r '.items | sort_by(.spec.nodeName)[] | [.spec.nodeName,.metadata.name] | @tsv'
+```
+The input for the `sort_by` command must be an array, we iterate the elements after the sorting.
+
+## Custom Columns and Sorting
+
+If all we need is a nicely formatted, sorted tabular report, `kubectl` has built-in support for powerfull sorting:
+
+```
+kubectl get po -o wide --sort-by=.spec.nodeName
+```
+
+Using `jid` to list pods sorted by node:
+[![asciicast](https://asciinema.org/a/36q5fxao2l8lta6ztf9akqciq)](https://asciinema.org/a/36q5fxao2l8lta6ztf9akqciq)
+
+The usage of Custom Columns with the knowledge of the data structure gained from `jid`, is also much easier:
+
+```
+kubectl get no -o=custom-columns=NAME:.metadata.name,AWS-INSTANCE:.spec.externalID,UNSCHEDULABLE:.spec.unschedulable
+```
+
+**Note**: apart from using `grep`, there is no easy way to filter.
+
+## Golang Templates
+
+If we do not wish to use `jq` (or have no access to `jq`) need filtering and powerfull output control, 
+we may use Kubectl's built-in support for golang templates (inline or from a template file on disk):
+
+```
+kubectl get no -o go-template="{{range .items}}{{if .spec.unschedulable}}{{.metadata.name}} {{.spec.externalID}}:{{end}}{{end}}" | tr ":" "\n"
+```
+
+I could not find an easy way to print newline characters with inline golang template, so used a trick 
+printing colons and using `tr` to convert colons to newlines.
+
+## JSONPath 
+
+Golang templates can be complicated and verbose - an alternative, if you are more familiar with `jq`-style queries, or `awscli`,
+is to use JSONPath.
+
+```
+kubectl get no -o jsonpath="{.items[?(@.spec.unschedulable)].metadata.name}"
+```
+
+Internally, this seems tightly coupled to the golang templates.
+
+Kubectl supports a superset of JSONPath, with a special `range` keyword to iterate over ranges, 
+using the same trick to add newlines:
+
+```
+kubectl get no -o jsonpath="{range.items[?(@.spec.unschedulable)]}{.metadata.name}:{end}" | tr ":" "\n"
+```
+
+More examples of using jsonpath can be found in 
+[the Kubernetes tests for the JSONPath utility](https://github.com/kubernetes/kubernetes/blob/v1.5.0-beta.2/pkg/util/jsonpath/jsonpath_test.go#L149):
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