Writing a Cloud Storage Trigger with Cloud Functions for Firebase; Part 2 - Firecasts Video Lecture | Beast Android Development: Firebase Necessities - App Development

hey everyone Jen person here I'm going
to show you how to take a cloud storage
trigger to the next level using the
admin SDK welcome to part two of writing
a cloud storage trigger with cloud
functions for firebase if you haven't
watched part one yet go ahead and check
it out and then come back when you're
finished
I'll be adding on to the code for the
function I created last time to address
some problems that I left open in the
last video I was building a photo app
where users upload pictures which then
get displayed in a grid of thumbnail
images I showed you how to trigger an
event from a cloud storage change create
a thumbnail using imagemagick and write
the thumbnail image back to storage but
what I want is a way to display the
image in my app and share with others
the easiest way to do that is through a
public URL fortunately I can add the
Google Cloud Storage SDK to my generate
thumbnail function to make the URL
accessible to the app I'm going to store
the thumbnail signed URL in the firebase
database so my app can find it assign
URL allow us access to the image much
like the download URL that you can
generate using the firebase Storage
Client SDK the sign URL provides access
to a file and storage without requiring
any form of authentication I'm going to
push a reference to my database with key
value pairs containing the signed URL
for the original image and the thumbnail
using the firebase admin SDK then my app
can read the URLs and display the images
here we go before I can request a signed
URL in my function using the Cloud
Storage API
I need service account credentials this
is because it requires advanced
privileges to authenticate my uploads I
do that from the firebase console in my
project by clicking the gear next to
overview selecting my project settings
and choosing the service accounts tab
under the firebase admin SDK tab I'll
select generate new private key
this downloads a JSON file containing
the service account credentials I'll add
this to my project functions directory
then in the and XJS file I need to add
the file name to the cloud storage
configuration
allowing me to use sign URLs now I want
to note that anything I put in the
functions directory gets sent when I
deploy I added the JSON file containing
the service account credentials to my
functions directory so that Google Cloud
Storage can access them one require is
called now in part one of writing a
cloud storage trigger I use NPM to
install the Google Cloud storage module
which looks like this
in order to use the firebase admin
module I'll need to use NPM to install
it just like I did with cloud storage
I'll do that now back at the terminal
I'll install the firebase admin module
using NPM install save firebase admin
now in the last fire cast many of you
pointed out that an NPM version 5 save
will be the default so you won't need to
include it as I have here if you're on
version 5 or later you can ignore the
part about using save but since not
everyone is using version 5 right now
I'll keep it here in my example then in
index jf I'll require the firebase admin
module in order to use the admin SDK I
need to call initialize app which
initializes an instance of the firebase
app I pass the firebase config directly
to initialize app to auto configure the
admin nodejs
SDK with the correct information about
my app I'll store a reference to the
root of the database to use later when I
add the image URLs I'm going to need the
file object for the original image in
order to get the signed URL I get this
object by calling the file method on my
storage bucket this method returns a
file object which contains data about
the file as well as the capability to
generate a signed URL that can be used
publicly to access the file I'm going to
add a constant called thumb file path
which will hold the file path for the
thumbnail you'll recognize the same
regular expression from the last fire
cast the get signed URL method of the
file class has one required parameter
config and config has two required
attributes action and expires config
also has a bunch of optional attributes
but I'll stick with action and expires
today action is what I want the
recipient to be able to do with the URL
in this case I only want them to view
the image so the action will be read
expires is the date when the user will
lose access to the URL for the
designated action for my purposes I want
to choose a date that is far enough out
to ensure the users will be able to
access the image as long as the app
exists I'm very confident in the life of
my app so I want to choose a date very
far in the future oh and by the way if
you'd like to learn more about sign URLs
as always check the links below
alright now I'll show you how to get the
signed URL here's where I left off my
cloud function generates thumbnails
I've already declared some file paths
globally so I'll remove this declaration
I want to add a reference to the
database after the thumbnail image is
successfully stored in cloud storage so
I'll use the then method I'll need the
file object for the thumbnail image just
as I needed it for the original image I
use some file path here as well I'll
create a constant to hold the values for
action and expires to pass as parameters
when I call get signed URL I'm going to
call the get sign URL method of the some
file object which returns a promise that
when fulfilled contains the URL I'll
call this method on both the original
image and the thumbnail as I want to
store both URLs in the database one call
to get signed URL doesn't depend on the
other so I can call the methods
concurrently
I'll return a promise containing an
array with two elements the URL for the
original image and the URL for the
thumbnail once I have an array of
promises I can get the signed URLs and
write them to the database the first
promise is from the thumbnail and the
second is from the original image each
promise returns an array with a signed
image URL as the first element I have
both URLs and I'm ready to add them to
the database the structure of my
database is like this I have a child
called posts that contains all the
images users post each post has a push
ID at the key this allows me to order by
key
when I query so that I can show the
newest photos at the top of the grid
then the value of the push ID is two key
value pairs one for the original image
and one for the thumbnail
let's get coding I define ref earlier as
a reference to the root of the database
I'll create a new reference in the
database child posts with a push ID
created by the method push I'll set the
value of this new reference with key
value pairs for the original images URL
and the thumbnail images URL then I'll
return the promise finally I'll run
firebase deploy from the terminal to
deploy the latest version of my function
now I can trigger this function by
manually adding an image to my cloud
storage bucket from the firebase console
but I have another option that enables
me to test my function faster gsutil
gsutil is a Python application from the
Google Cloud SDK but lets you access
cloud storage from the command line you
can use gsutil to do a wide range of
bucket and object management tasks
including uploading objects this can cut
down on testing time because I can type
much faster than I can select an image
from a list furthermore I can write a
script to upload the images to make it
even easier to test but I'll save that
for another day want to know more about
gsutil check out the links below now
install the cloud SDK so I can get a
hold of gsutil first I'll check to make
sure I have the version of Python that's
required to run the Google Cloud SDK you
can check using the links to the
documentation which is provided below
today the doc says that I need Python
2.7 point 9 or later so I check that on
the command line in a moment you should
also verify your version it's up to date
with what it says in the documentation
while I'm checking the required version
of Python I'll download the software now
I'll check my version of Python on the
command line looks good I'll unpack the
file then run the install script to add
the SDK tools g-cloud will make changes
to my bash profile to enable me to use
shell commands I'll select yes to allow
this I'll press ENTER to update the run
command file I'll open a new terminal to
let the Cloud SDK commands appear in my
shell path I'll run which g-cloud from
the
man line to show the path where the SDK
is installed finally I'll run g-cloud
init to initialize the SDK when I run
g-cloud init I'll be prompted to login
I'll do that now and then return to the
terminal I select my firebase project as
the default I don't need the g-cloud
compute component so I'm going to say no
here and now I'm ready to use gsutil on
the command line now that I've installed
the cloud SDK command line tools I'm
ready to upload images using gsutil the
gsutil commands CP is used to copy files
and objects between the local file
system and the cloud
copy data within the cloud or copy data
between cloud storage providers I'm
going to use CP with the location of the
image I want to upload and my cloud
storage bucket to copy the local image
to my bucket here we go I'll call gsutil
CP from the command line with my image
location and my cloud storage bucket I
get a message confirming that the image
was uploaded I can then check in the
firebase console and confirmed that the
thumbnail is created when I click the
thumbnail I can check out its metadata
then I can select the database tab and
see that a child is added to the
database
it contains the urls for both images so
I know the function did its work I now
have a cloud function that's triggered
when an image is added to storage it
creates a thumbnail of the image and
right saddest orage and then pushes a
database reference containing the urls
to the images and all this happens
outside the client app and works across
platforms you can see just how powerful
cloud functions can be so did you learn
something cool want to learn more then
be sure to subscribe to the firebase
channel on YouTube to get notified about
new fire casts on cloud functions and
other firebase features also check out
the sample code on github to see all
sorts of ways to use cloud functions the
documentation and sample links are in
the description below thanks for
watching and I'll see you right here on
another episode of fire casts
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